We’ve rebuilt since The War.  We’ve founded hundreds, some say thousands, of colonies since the Shang left.  It’s hard to say what a colony is nowadays.  We’ve repaired what damage we can, and we’ve learned a ton about bringing worlds back from nuclear winters.  I’ve visited a lot of those worlds, new and old.  Not all of them by any means.  If I live forever, I’ll probably never see every world we’ve colonized.  There are always new colonies after all.