In short you can upgrade your CPU if it's a model that is not soldered onto the motherboard.
However there are several things to consider. First of all the technical part: TDP must match, socket must match, DDR support must match.
Now for the common sense part: Any upgrade will have minimal impact on performance ( 10% at most). Any upgrade attempt may result in damage if done by someone unskilled with laptop MB's.
Paying for the operation is not worthwhile.
Laptops are used for mobility and not performance so if you use your laptop on a desk with mall bought desk coolers connected to your usb port, while using usb expansions for any other gadgets you might not need a laptop at all.
To be short. Don't ever think about it.