I'm sure there are exercises that you can do to improve the skin texture and the facial muscles which would help but everything I've ever read about skin firming after weightloss says that no cream has the power to restore elasticity to any major degree. That's why people have tummy tucks and face lifts etc to get rid of excess skin. I suppose it depends upon the extent of the problem as you perceive it to be.
I use a nifty little gadget from the body shop on my face for this reason. It's like a little spiky roller and you use it with your choice of moisturiser. It's supposed to promote collagen I believe and to help the skin to shed antioxidants and improve oxygen. Whether it works I have no idea but I'm nothing if not a sucker for a gadget.