ajax message script problems

I have a ajax script that posts messages to mysql and displays the message in on the page via ajax.

I like the function, but I when I refresh the page the message disappears. :'(

PHP INSERT:

if(isset($_POST['message_wall'])){
    /* Connection to Database */
    include('config.php');
    /* Remove HTML tag to prevent query injection */
    $message = mysql_real_escape_string($_POST['message_wall']);
   
    $sql    =    'INSERT INTO wall (message) VALUES(
                "'.$message.'")';
                 mysql_query($sql);
        
echo $message;
                 } else { echo '0'; }

AJAX CODE:

<script type="text/javascript" src="jquery/jquery-1.3.2.min.js"></script>
<script type="text/javascript">
$(document).ready(function(){
    $("form#submit_wall").submit(function() {

    var message_wall = $('#message_wall').attr('value');

        $.ajax({
            type: "POST",
            url: "insert.php",
            data: "message_wall="+ message_wall,
            success: function(){
                $("ul#wall").prepend("<li style='display:none'>"+message_wall+"</li>");
                $("ul#wall li:first").fadeIn();
            }
        });
    return false;
    });
});
</script>

HTML DISPLAY AREA

<ul id="wall">
</ul>

I have tried using a select statement in insert.php but it does not work.

How can I insert and then select data to display without loosing it on refresh or next visit?