Sell your laptop, and get one with CPU you want.
Your "slow"processor is chosen to match the thermal profile that laptop supports. This is the list of tasks:
- you find someone to de-solder BGA chip off your motherboard
- prepare the motherboard for new CPU
- find an i5 CPU in FCBGA1170 socket, with same TDP as original
- solder it back into the board
- hope that the existing BIOS will run (since I doubt you will find BIOS for that laptop with i5 support)
- finally, throw everything in the garbage - your $400 laptop, your $200 CPU...
So.. You will be out $250 for parts, another $150 for labor. You are $100 short of new laptop.