My goal is to beat the final boss so you can ignore reasoning that includes achievements/unlockables/highscores.
After reaching the 4th teleporter you can choose to warp to the final level or replay previous levels. When should you choose to replay levels and not warp right to final level?
There are plenty of chests and you can farm experience in the last level before the boss. If your goal is to defeat the final boss, is there ever a reason to repeat levels?