yeah you technically can upgrade cpu's on laptops as long as they're the same sockets, my old hp g61 from 2009 has a single core sempron m100 1.99ghz and I thought of getting a Turion dual core for the hell of it. That single core is just horrible, uses almost all cpu power just on facebook lol.
It's just a pain to do, the cpu is under the keyboard. Just look up a disassembly video on youtube of your laptop. On my newer quad core APU llano laptop the cpu was very easy to replace the thermal paste on, it was located on the bottom of the laptop. It says the socket of mine is Socket S1 (S1g3). Make sure the TDP is the same, like, if your current is 25w I wouldn't use a 35w one for example. It would likely overheat.