You'll need to get in contact with Sony about this one.
The three things you'll need to ask them are:
1) Is my CPU soldered into my motherboard?
2) If I can replace my chip, what is the highest model CPU that my BIOS can support?
3) What is the safest CPU I can put in without overheating my laptop?
I personally don't recommend upgrading laptops like this. Your money would be better spent saving up for a new laptop, not throwing it at a high-cost CPU upgrade on an older model.