I'm guessing that elements and system that you've made before can be repurposed. I have a random-walk maze generator that I've heavily modified and used in almost all of my games. The text file reader and dialogue systems in my games are also largely reused. I'm guessing that if you want to make a camera game similar to this year's submission with most of the same code but a different main character you'll need to list it in the "started early" section. If you just use the code from your clothing menu and make an RPG game where you can equip different items you probably don't need to mention where parts of the equip menu originally came from.