<div class="form-group">
   <div class="input-group">
      <span class="input-group-addon" id="input-group-addon-captcha"><img id="cap-img" src="captcha.php"></span>
      <input id="seo-captcha" name="" class="form-control" placeholder="Please Enter Text" type="text">
      <span class="input-group-addon seo-addon-right"><button class="btn btn-xs btn-q" id="reload"><span class="glyphicon glyphicon-refresh" aria-hidden="true"></span>
      </button></span>
   </div>
</div>

  <script>
  $(function() {
    $('#reload').click(function(){
     $('#cap-img').attr('src', 'captcha.php?' + (new Date).getTime());
    });
    });
 </script>