Working example: http://jsfiddle.net/brBdD/21/
var tag = '<li><input type="checkbox" name="checkbox-5a" id="checkbox-5a" data-iconpos="right"/><label for="checkbox-5a"><img src="https://fbcdn-profile-a.akamaihd.net/hprofile-ak-ash4/261025_100001129460073_937883521_q.jpg" style="margin-right:20PX; float:left" width="35" height="35"/>Roy dffaf</label></li>';
$('#FB').append(tag);
$('#FB').find('#checkbox-5a').checkboxradio().checkboxradio( "refresh" );
$('#FB').listview('refresh');
In your case .listview('refresh');
will only style listview and listview only, don't forget you also have a checkbox to style. Because of how jQuery Mobile works you first want to style checkbox and then listview.
Checkbox is usually styled with .checkboxradio( "refresh" );
but in this case we have a dynamically created checkbox so it first needs to be initialized with .checkboxradio()
.