Well, I'm pretty sure we all know about Jericho already (which is the show that immediately comes to mind when this sort of discussion is brought up), but that was live-action.
As far as animation, nothing comes to mind that hasn't already been mentioned. Home Movies was what I was thinking of, but somebody already beat me to the punch (just to clarify, though; it was actually cancelled again in 2004, not 2003).
Ooh... wow, my head hurts just thinking about that "revamp".
The film of those episodes should be thrown in a hole somewhere and burned. I just couldn't believe what I was watching when they brought it back. That abomination was not the Dexter's Lab that I came to know and love.
Sorry if that sounds a little harsh, but... they should have just left the show alone after the first run. There was no reason to bring it back if their plan all along was to throw everything out the window, and start from the ground-up; it didn't need that at all.