How to loop through replacing span with XML array items

How to loop through replacing span with XML array items

My website has a flash animation I'd like to replace with a jQuery animation (www.theshredstop.com).  I'm trying to create a dynamic statement to grab an array of words from an XML file and loop through replacing the word in a <span> with a random item.  Would like it to loop continuously while the page is displayed.  The HTML statement is:

<p style="text-align: center; font-size: 2em; font-weight: bold; margin: .5em,0,.5em,0;">
      <span>Shred your </span><span id="indexShredItem">paper</span><span>, not your nerves.&#8482;</span>
 </p>

Here is the script I'm using:

$(document).ready(function() {
    $('#indexShredItem').delay(1000).fadeOut(1000, function () {
        $.ajax({
            type: "GET",
            url: "shred_items.xml",
            dataType: "xml",
            success: function(xml) {
                var rndItem = new Array();
                $(xml).find('item').each(function(){
                    var itemArray = $.makeArray($(this).text());
                    rndItem.push(itemArray);
                });
                var rndNum = Math.floor(Math.random() * rndItem.length);
                $("#indexShredItem").replaceWith('<span id="indexShredItem">'+rndItem[rndNum]+'</span>');
            },
        });
    });
});

It works great once, but I can't get it to loop.  I've tried "for" and "while" loops (no loop attempt is in the script above).  Any ideas?