I would trash the entire trilogy and start all over again. Focus on an aging Luke right from the start and follow as he recruits a group of new characters for a specific reason that is "resolved" in movie 1, then have someone from that group evolve into the antagonist for the remaining two films as the new characters face split loyalties, betrayal, finding their inner strength etc, and then let one of those characters slowly emerge as the new hero by the end of the third movie.
Or you could just have another go at a Death Star, I guess.