I believe so, but then it would be out of reach of some of the spacecraft which service it. In particular, the Shuttle could not reach it. Seriously. Shuttle can reach Hubble's higher altitude only because the Hubble orbits in the ideal inclination from Florida -- about 28 degrees. ISS, on the other hand, orbits at the ideal inclination from southern Kazakhstan, so that it can be easily reached by Proton and Soyuz (more like 51 degrees, IIRC). Basically, Shuttle has to shift into the right orbital plane as well as climbing to the right altitude, and that takes energy too.
I seem to recall that ISS was temporarily boosted to a higher altitude than Shuttle could reach. That was in the year following the Columbia accident; the higher boost allowed Russia to go longer between reboost maneuvers, since there wasn't any need to keep it low enough for Shuttle to visit. I suspect that one Shuttle is retired, ISS will again fly a bit higher from time to time.