According to Deadline, Cohan’s current six-episode contract is exactly that, and any further appearances in this season or another would require another round of negotiations.
Of course, it’s possible the six-episode contract was held up by certain details that wouldn’t be an issue the next time.
At this point, Lauren Cohan is contractually allowed to return to film more Walking Dead episodes during the production hiatuses for Whiskey Cavalier, though we’re not sure how any of those hiatuses would match up with the zombie drama’s Georgia-set production.
Should the process be as troublesome as it was this last time, it wouldn’t be unquestionable for the actress to choose not to keep returning.