Wasn't where to put this, so here goes.

If I get an agent to represent my novel, they sell it, and it does well, is it okay in the future to skip the query process? Could I just call them up and say "got another one for ya!" or would I have to go the usual route again?

I'm sure this is kind of case-by-case thing and would be up to the agent, I was just wondering if there was some kind of standard I wasn't aware of.