I want to exchange my laptop and buy a gaming CPU. Plz Help

Hi frnds. I need ur advice on exchange my laptop and buy a gaming CPU.

My Laptop is DELL INSPIRON 15r N5010.

Specs:
Core i5 (I Gen)
4 GB RAM
500GB HDD
ATI RADEON HD4650

I was able to play games FIFA 14, Battlefield, etc.,

But i cant play FIFA 15 Demo, NFS RIVALS. My Graphic card is not good enough i guess.

So thought to exchange it and buy a gaming CPU(Of course by paying extra bucks)