Star Trek: Enterprise at first looked fresh/went with a fresh start but the quality went downhill after a couple of seasons. It used the appearance of the occassionally seen Andorians and the time travel concept in a desperate attempt to keep the viewers' interest and stay fresh. But it lasted a few seasons despite gimmicky attempts.
Star Wars: The Revenge of the Sith, whose storyline was executed poorly. Anakin's epic downfall as a Jedi knight was used as a gimmick to keep the story fresh but it didn't do much for me.
"Indiana Jones and the Last Crusade" lost the freshness of the Indiana Jones storyline, because it bears a lot of similarity to the first film.
Batman Returns fails to stay fresh, when the tone of the movie become too gothic, too grim, too gloomy for the audience.