When he does revisit a particular theme, he doesn't tend expand on it at all. Royal Tenenbaum and Steve Zissou are practically the same character (and Mr. Fox too, with some stretching) and they both develop from a similar experience in the same way.
Similarly, the Darjeeling Limited adds nothing on top of The Royal Tenenbaums. It reuses the same ideas, reset in a different location.
That isn't to say they aren't good films individually, but as a body of work, it's repetitive.