That is because you need to restyle listview after new content has been added.
Do it like this:
$('#listviewID').listview('refresh');
Sometimes when listview is generated dynamically it will require you to initilaize it before it can be styled, so in that case use this:
$('#listviewID').listview().listview('refresh');
Working example: http://jsfiddle.net/Gajotres/LrAyE/
And this is a working example out of your example: http://jsfiddle.net/Gajotres/HuKab/