There is a function in the editor which says 'saving' or 'saved', click on it and you should be able to restore it to a previous version because it leads you to a history webpage of your repl.
Lol, its hardly a "Hack"
@JacksonCowie It is a hack. While the "backdoor" in this case is only the history editor for the repl, it still qualifies as it was performed with ill intent and without the permission/knowledge of the owner. so although it's not a true hack, it still qualifies as it also killed multiple user's submissions for the Hackathon.