When you first get control of Vincent at the bar, go to your phone and save. Then, head over to Rapunzel and play your 3 credits. The game saves after each level you complete, but it is only saving your progress in the Rapunzel game and not in your main game save. Therefore, simply exit out to the Main Menu without saving after you leave the Rapunzel game and then reload to find yourself back where you left off at the Stray Sheep. You will still have your 3 credits for Rapunzel and be able to start at the next level in the game you last left off at.