Function in javascript won't update directly, have to refresh page

In my javascript

$(document).ready(function() {
    console.log((new Date().getTime() / 1000));
      if ((new Date(setting.lastDate).getTime() / 1000) <= (new Date().getTime() / 1000)) {
        //alert("reach");
        $('.Go').removeAttr("disabled");
        $( ".headertesting").replaceWith(" ");
        $( ".testing" ).replaceWith( "<span class='butlabel testing' >Register Now!</span><span class='spier'></span>" );
      }

});

In my html when i run this function . It's not worked as i expected I have a countdown date: Example i set

lastDate = "06/01/2016 10:21:00"

So it will check my currentTime and compare it. But when it reach. the button didn't update directly. I have to refresh the page only see the result. What i want is directly button change without refresh page once time reached.