I am encountering an issue with the .droppable event. I have set up two sections where I can move elements, but every time the page is refreshed, the positioning of the elements reverts to the initial position. How can I maintain the last positioning of the elements even after a page refresh?

Sample: http://jsfiddle.net/jhogervorst/CPA5Y/

HTML:

<div class="group">
    <h1>Group 1</h1>

    <ul class="parent">
        <li class="droppable"><span class="draggable">Item 1</span></li>
        <li class="droppable"><span class="draggable">Item 2</span></li>
        <li class="droppable"></li>
    </ul>
</div>

<div class="group">
    <h1>Group 2</h1>

    <ul class="parent">
        <li class="droppable"><span class="draggable">Item 3</span></li>
        <li class="droppable"></li>
        <li class="droppable"><span class="draggable">Item 4</span></li>
    </ul>
</div>

CSS:

* { margin: 0; padding: 0; }
body { font-family: Helvetica, Arial, sans-serif; }
h1 { font-weight: bold; margin-bottom: 10px; }

.group {
    width: 150px;
    margin: 5px 0 5px 5px;
    float: left;
}

.parent {
    list-style-type: none;
}

.parent li {
    height: 41px;
    margin-bottom: 5px;
    padding: 5px;
    background: #ddd;
}

.parent li.active {
    background: yellow;
}

.parent li.hover {
    background: orange;
}

.parent li.hover span {
    opacity: .5;
}

.parent li span {
    display: block;
    height: 25px;
    line-height: 25px;
    padding: 5px;
    background: #eee;
    border: 3px solid #eee;
    cursor: move;
}

.parent li span.ui-draggable-dragging {
    z-index: 10;
    border-color: red;
}



$(".draggable").draggable({
    revert: true,
    revertDuration: 0
});

jQuery:

$(".droppable").droppable({
    activeClass: "active",
    hoverClass: "hover",

    accept: function (draggable) {
        // The droppable (li element).
        var droppable = $(this);

        // The droppable which contains the draggable, i.e., the parent element of the draggable (li element).
        var draggablesDropable = draggable.parent();

        // Is the draggable being dragged/sorted to the same group?
        // => We could just sort it, because there's always enough space inside the group.
        if (droppable.parent().is(draggablesDropable.parent())) {
           return true;
        }

        // Nope, the draggable is being dragged/sorted to another group.
        // => Is there an empty droppable left in the group to which the draggable is being dragged/sorted?
        else if (droppable.parent().find(".draggable").size() < droppable.parent().find(".droppable").size()) {
            return true;
        }

        // Nothing true?
        return false;
    },

    drop: function(event, ui) {
        // The droppable (li element).
        var droppable = $(this);

        // The draggable (span element).
        var draggable = ui.draggable;

        // The droppable which contains the draggable, i.e., the parent element of the draggable (li element).
        var draggablesDropable = draggable.parent();

        // Is the draggable being dragged to it's own droppable?
        // => Abort, there's nothing to drag/sort!
        if (droppable.is(draggablesDropable)) {
            return;
        }

        // Is the draggable being dragged to an empty droppable?
        else if (!droppable.find(".draggable").size()) {
            // Just drop the draggable there.
            droppable.append(draggable);
        }

        // Is the draggable being dragged/sorted to the same group?
        // => We can just sort it, because there's always enough space inside the group.
        else if (droppable.parent().is(draggablesDropable.parent())) {
            // Is the draggable being dragged up?
            if (droppable.parent().find(".droppable").index(draggablesDropable) > droppable.parent().find(".droppable").index(droppable)) {
                // Add the dragged draggable's droppable before the droppable.
                draggablesDropable.insertBefore(droppable);
            }

            // No, the draggable is being dragged down.
            else {
                // Add the dragged draggable's droppable after the droppable.
                draggablesDropable.insertAfter(droppable);
            }
        }

        // Nope, the draggable is being dragged/sorted to another group.
        // => Is there an empty droppable left in the group to which the draggable is being dragged/sorted?
        else if (droppable.parent().find(".draggable").size() < droppable.parent().find(".droppable").size()) {
            // Find the first empty droppable in which the draggable is being dragged/sorted.
            var emptyDroppable = $($.grep(droppable.parent().find(".droppable"), function (item) {
                // Are there draggables inside this droppable?
                // => Return TRUE if not.
                return !$(item).find(".draggable").size();
            })).first();

            // Clone the dragged draggable's droppable before itself, because we need to remember its position after moving it.
            var draggablesDropableClone = draggablesDropable.clone().insertBefore(draggablesDropable);

            // Is the draggable being dragged above the empty droppable?
            if (droppable.parent().find(".droppable").index(emptyDroppable) > droppable.parent().find(".droppable").index(droppable)) {
                // Add the dragged draggable's droppable before the droppable.
                draggablesDropable.insertBefore(droppable);
            } else{
                // Add the dragged draggable's droppable after the droppable.
                draggablesDropable.insertAfter(droppable);
            }

            // Remove the position of the dragged draggable, as there may still be some residual CSS from the dragging.
            draggable.css({"top": 0, "left": 0});

            // Add the first empty droppable before the cloned draggable's droppable. Then remove the latter.
            draggablesDropableClone.before(emptyDroppable).remove();
        }
    }
});