To be fair, some people updates their games after deadline, I saw it in a submission feed, guess you could also update yours since it is just to make a game at least playable. But in case, I am a newbie to game jams, so I don't really understand rules entirely, so I guess, it is up to you to decide
Ok, I actually searched about this problem https://itch.io/jam/lowrezjam2016/topic/20616/can-we-update-our-games-later-post...
Here are no specific rules about post-game jam updates, so the answer from there could be applied here also. In short, you can update post game jam. Though I would add, to keep the spirit of game jam, I wouldn't recommend adding new features/levels and so on.