Don't do anything just yet. The first thing I would do is increase the current from the controller by about 25% to 30%, which is often easy and doesn't cost anything. The extra current gives the motor more torque and power, so it will climb hills better, but it won't have a higher top speed.
To increase the current, you add a bit of solder to the shunt in the controller. For that, you need to open that compartment at the bottom of the downtube. Inside is an aluminium box. In some instances, you can access the shunt under the endplate opposite the wires end, so unscrew that first to have a look. If you can't see it, unscrew the screws in the end with wires coming out of it and the three screws in the side, then you can slide out the insides.
This is general advice for an ebike. Until you open yours up, we can't be certain that this mod is possible on yours, but the probability that it'll work is pretty high.
Here's the sort of thing you are aiming at. If you decide to go ahead, ask again before adding the solder for precise advice.
Before
After