In general, there is little point to getting a larger power-supply for laptops.
Using a larger power supply makes sense for desktop computers since it allows you to install more components like drives and such that draw a lot of power.
With a laptop however, there is little room for adding components. A wired keyboard and mouse will consume a little bit of power, but certainly nothing that will require a larger power-supply.
The most power-consuming components that you can add to a laptop will be bus-powered USB devices. Obviously using a larger power-supply will allow you to chain more of them (e.g., through a non-external–powered hub), but unless the laptop is from a cheap manufacturer or a super-cheap model, then the power-supply that is provided with it will be rated to be more than the laptop’s maximum draw by at least a small margin. This allows you to add several power-drawing components to each of the ports and usually still have some unused capacity.
You can determine your maximum power draw with a meter like the Kill-a-Watt (your local library may have them for loan). Plug in all of your components and run a 3D game and see how high you can push it. Then you’ll know for sure if you need a larger power supply or not.