The laptop should have a standard MXM-III slot, which means you should be able to replace it with any MXM-III graphics board. It's hard to find out for certain, but I believe the layout is fairly well defined, so the heat sink should fit properly.
That's not to say that finding MXM cards on the retail market is easy. I'm able to find a few, but none are especially cheap. This place might be your best bet. You can contact them and get some more solid information before buying.