If you were given the feedback that your case performance was borderline, I'd expect you to be tested on this again.
Beyond this however, final rounds are notoriously hard to anticipate: senior principals and partners will sometimes take the discussion in seemingly random direction, all the while paying close attention to how well you engage in the discussion, build rapport and think.
To prep, id do the following:
1. Review case interviewing skills, obviously
2. Review the standard fit questions
3. Expect the unexpected, don't let yourself stress out if the interview isnt going as excepted - it is probably ok