The laptop memory you can upgrade (4GB).
But I agree that's enough memory for just about everything.
But by the looks of your post it looks like you would like to upgrade the the GPU memory. First, you can't upgrade GPU memory. If you have 512MB your stuck with 512MB.
Second, you would not see an increase in your frame rate. You just need a better GPU.
In laptops is not easy and sometimes not even possible to upgrade the GPU. I would call the manufacturer of your laptop and see if they have any GPUs available for your laptop that are higher performance than yours. Don't be surprised if they have nothing to offer. Most laptops are made with only 1 or 2 GPUs in mind and they are made to fit that specific laptop. (Because the components are small and there are very few laptop standards.)
That is why the other 2 people suggested you lower your games' graphics setting.
That or get a desktop. If your a gamer desktops rule because they are easier to upgrade and the standards allow for many different components.