Unsupervised-->supervised on apple configurator

I currently have 30 iPads for my school but started out with only 8. Back then I decided to give each iPad an individual Apple ID (owned by the school) and I was manually adding apps. Our number has grown and teachers are starting to explore new apps, so I started using the Apple Configurator to mass install free apps (unsupervised). Now I run into the problem where the free apps need to be updated and its my personal Apple ID that was used for the configurator. My principal is seriously considering buying a mac so the school can use the configurator (rather than myself on my personal macbook) but how do switch all the iPads to supervised use without having to reload all the purchased apps? I'm also a little scared to put my VPP codes into the Apple Configurator because I've had problems with redemption codes already. Any advice??