(LuKiss) This so-called "glitch" allows you to retain your upgraded attack moves. During the game, as you gain enough coins to upgrade your attack moves, do it. As you finish each level, save your progress. Now, if you encounter a difficult opponent and get killed, when the game asks you to either "Restart" or "Quit", select "Quit". This is much longer of a process compared to just restarting. However, after you quit and reload the previously saved level, the upgraded attack moves still remain. You can use this method to level-up your attack moves by intentionally die (like, in a fire) and quit-and-reload the game several times.