No upgrading allowed, This game does not allow you to restart or revisit past levels, once your done YOUR DONE. you have 2 options.
1 - Play each level until you have one star and then finish the level. Should take about 1-3 hours. I have found that this game is a bit buggy and progress could be an issue such as 100% levels not being achievable due to bugs, 2+ Playthroughs if you go for this way, atlease on your other playthroughs you get to see the upgrades.
2 - Start a playthrough and never upgrade, get 5 stars, 100% and once finish the last level (15 in total) it will unlock, you could then also unlock the Infinite Power Achievement at the end of the game. Fingers crossed you don't come across any issues while cleaning.