$(document).ready(function () {
    make();
});

function make() {
    var currentTime = new Date()
    var extend = currentTime.getMilliseconds();
    $.ajax({
        url: '/custom/ajax/ajaxpanel.aspx?ext=' + extend,
        success: function (data) {
            $('.footer').html(data);            
            setTimeout(make, 7000);
        }
    });
}