Mind you, if one lone starship stranded in the Delta Quadrant cut off from the rest of the Federation can restore itself to pristine condition within a week of taking on massive damage, then it should be comparatively super easy, barely an inconvenience for Starfleet Command, right smack dab in the middle of the Federation with access to all the Federation's resources to be restored within six months of being obliterated.
Truth be told, I was more bothered by the fact the people you see in the establishing shots were wearing outdated uniforms. Yes, that's because those shots were taken from Homefront/Paradise Lost, but it irritated me all the same.