That’s probably not a good idea. To retune it from C to the G above and so forth on up the harp would tremendously increase the overall tension on the harp, probably far beyond that harp’s tolerance.
You *might* be able to retune it from C to the G below, but if you use the current strings they will end up slack enough that they’ll sound more like rubber bands. If you change the strings, you’ll have to use thicker ones, which will change the tone — probably not for the better.
If you decide to experiment, let us know how it goes!