What processor do you have at the moment?
And as 13thmonkey said, the GPU could be limiting your gaming performance too. GPUs in laptops are generally impossible to upgrade as they are soldered to the mainboard.
But processors are often (not always) removable and able to be upgraded. But putting a more powerful one in could cause your laptop to overheat, so it is risky business.
I'd get a new laptop
Do some research to make sure you get one that can do what you want it to do.