There is a way to have unlimited saves in normal and expert modes. When you enter the menu and save, notice the red save status bar. When the bar is nearly complete, hold Start. This will exit out of the menu and go into the game before the game registers the save. Occasionally it may register a save. To lower the chances of this happening, save your games in a rotational manner. In other words, save in the top slot, then the second, then the third, then save back up to the first one again and repeat.