It's possible, but unless you have worked on laptops before, it's a major PITA. You'll also have to find a chip that matches the socket and the TDP (power requirements) of the old chip. If you do, it may not be much of an upgrade and it may not be worth it.
Exactly. It's usually not worth the cost of the upgrade because of the expense of notebook processors and the minor differences in performance the next up model will provide.
Why do you want to upgrade? Perhaps we can help with an alternative?