I didn't mean to keep operating it, but to use it for spare parts or as a container, to shield new gear from those perky micrometeoroids.

The ISS must be ~ 2/3 (?) of escape velocity and out of the densests layers of the atmosphere, so it seems reasonable (to me, at last :) that the power needed to boost it is much less than what it took to put it where it's at.

GEO is very densely populated, maybe a repair shop in the neighborhood would attract some customers.