Once you’ve submitted a game to the jam, you should be able to update it just by uploading a newer version to itch. Once the jam’s completed, however, you won’t be able to update it until after the voting period has finished (which might be a week). But after that, you can do as many updates as you have motivation to keep working on! … I still need to make some updates and fixes to my last jam game :( I’ll get around to it… eventually