Sharpen?
use it till some wear starts to show ... by then you should have an idea if it needs any sharpening.
outside of that; penetrating and downward sawing motions leverage the effectiveness of the forward slant of each tooth, at least ensure they are "sharp". file on the existing angles, don't make new ones. no need to grind unless working out burrs or damage.
the lesche tool monopolizes the catching and cutting of sepperated hooked serrations which literally draws the cutting motion forward naturally. in theory, you could use a "rat tail" file and whittle out similar curves in the teeth of your tool. look at lesche tool pics closely. a lot of metal will need to be removed, but possible.
otherwise, that is a nice gift.