Again, I think you're wrong. They only "repair" because instead of putting up that ship that had been hit last round, they put up a new ship that hasn't been hit yet. This makes it look like you're repairing ships, but fight the fleet enough and eventually they have to put in a damaged ship. I think if you have a turn or two between battles they repair (remove the yellow ring) - or it may have to land on a planet.
Daves own post pointed out that he doesn't carry over damage between battles.
