Frank,

Most likely the heating element determines the wattage. I'm guessing that
you have a mini hot plate so it would be difficult to upgrade the wattage. I
looked around on the net and most of these ot plates don't have a wattage on
their ads. You could try a bigger hot plate such as those designed for a
carafe.
And of course there's the microwave oven or sterno.

Dave M.