how hard is it to just assume that they're making repairs between episodes. It's not like each episode took place the very next day from the one before, there are weeks if not months between episodes, plenty of time to make any repairs.
It isn't, and I imagine there were more stops at hospitable alien ports than we saw. The problem isn't voyager getting repaired, but rather that it always looks so pristene and standard-issue.
Other trek series had the same issue to varying extents, like DS9 never looking that damaged, but in Voyager it should have been played up a lot more as issues of survival and resources were closer to the show's core premise. (And Enterprise actually got this right, with the ship spending half of season 3 looking totally battered.)