It might be possible, it might not. On some laptops, the CPU is soldered to the motherboard, on others it's in a socket. Even if it is in a socket though, laptop CPUs are hard to find and expensive, so I wouldn't recommend it. There's also no guarantee that your cooling system was designed with the higher power i7 in mind.
i've checked and it's on a socket, so I can take it out but the problem could be the cooling system. I've a core i5 so core i7 might not be too much hot that this one.
I tell you this because some friend has a core i7 laptop processor and he sells it to me very cheap.
do you think that this processors use the same socket? I don't know
Even if you can find a suitable i7 and physically install it, it may not be recognized by the notebook's BIOS. I would only proceed with this endeavor if your model of notebook can be purchased with the option to include the i7. That way, you know that the BIOS issue should be fine.
The heatsink/fan issue is likely not your limiting factor here. CPU compatibility is.
They may or may not use the same socket. You can look that up on Intel's website if you know the actual CPU numbers (not just "i5" or "i7", but specifically "i5-xxx" or "i7-xxxx". Also, COLGeek brings up a good point about the BIOS.