The process for this is to post it as "incomplete" now, submit your 7DRL version (if you want!), and continue working on it :)
Itch.io will allow you to continue uploading new versions of the game even after the 7DRL is over (there is nothing blocking that), however, we are asking people to honor the rules of the challenge and provide a 7DRL version (especially if they mark the game as "Completed") so that both players and jurors can experience the original game.