I have NEVER seen a laptop with a cpu soldered to the motherboard and I have personally serviced over 1000 laptops and hundreds of different models. A CPU costs at most a couple hundred bucks, the board is usually triple that or more, manufacturing a dust busting machine where cpu failure is certaily possible isnt cost effective, 99.999% of all laptops have sockets for CPUs and are at least replaceable, if not upgradeable to an extent. Depends on if that line of laptop has any
headroom, if there is a model above that with a faster processor, more than liekly you have the same board and you have every possibility to put at least up to that speed if not faster (if the socket is the same along with voltages and power consumption).