Why Can't I get my google maps to update lat/lng on button click?

I am trying to get my center location to change on my google map based on a button click. I have more functionality to add later, but I can't get this basic update to work. I have a default value that loads on page load. The button should set a new location, but I see that it does update but then is quickly overridden by the default value because the page loads again.

I am new to google maps, and I am just trying to figure out how to load and interact with the map correctly.

Here is my code:

         <script src="http://ift.tt/13qgtmt"></script>                                                        
<script>

    var deanLat = 43.0843816;
    var deanLong = -89.5302394;
    var deanAddress = '1277 deming way, madison wi';

    var stmaryLat = 43.0592730;
    var stmaryLong = -89.4015130;
    var stmaryAddress = '700 S Park St, Madison, WI 53715';

    $("#FindDean").click(function() {
       refreshMap(deanLat, deanLong);
       });

    function alertme(message) {
          alert (message);
      }


    function refreshMap(ilat,ilong) {
       ilat = typeof ilat !== 'undefined' ? ilat : stmaryLat;
       ilong = typeof ilong !== 'undefined' ? ilong : stmaryLong;
        alertme(ilat);
        var mapOptions = {  
                zoom: 16,
                center: new google.maps.LatLng(ilat, ilong)
            };

        gmap = new google.maps.Map(document.getElementById('mapholder'),
          mapOptions);
    }


    function loadScript() {
      var script = document.createElement('script');
      script.type = 'text/javascript';
      script.src = 'http://ift.tt/1lrRXYd' +
          '&signed_in=true&callback=refreshMap';
      document.body.appendChild(script);
    }
   window.onload = loadScript;