BRL, most laptops graphics are chips that are often surface mounted to the motherboard ie permanently attached. This means the interface to the chip is also built in to the motherboard. They don't usually use a slot in board with additional electronics to take care of the communication between the graphics chip & the motherboard by presenting a standardised interfaceas desktops do.
That's what makes swapping graphics in a desktop so easy. There's a standardised interface that all graphics cards designed for that interface use, then the voodoo on the graphics cards does extra stuff to safisfy the graphics chip itself. That's why different brands & capability graphics chips can be used in a wide range of PCs
Some laptops have a plug in chip for the graphics. In this case you **might** be able to find a newer graphics chip from the same manufacturer that is pin & interface compatible with the old chip. Wouldn't hold out much hope though.