Generally, the only way to get more power out of an electric motor is to put more volts in, but that won't work on a scooter, for 2 reasons: a) there's no space for more/bigger batteries; b) the motor wouldn't take it anyway, because, for space and weight-saving reasons, they don't install a bigger motor than they need to for the amount of battery power available. So the short answer is, you can't.
