I've been doing some research and it seems as though your only upgrade path would be within the Sandy Bridge (2xxx) series of chips. Ivy Bridge may or may not fit, but even if it did the laptop bios would reject the newer CPU and no bios updates are available.
Within the Sandy Bridge line, the 2860 QM is available. You're looking at spending $500+ for one though.
Also, that is likely just a higher clocked version of the same chip. It's doubtful that your laptop's cooling solution would be adequate to accommodate a 3.6 GHz chip. Also, there is the question of power consumption and whether or not the included power supply system would be sufficient.
Honestly, I would keep what you have. It's a very strong chip. That graphics chip...