I recently started uploading some of my games to itch and I’ve been wondering, does data from the previous version of a game carry over to the new one? I want to make sure if it does so that I can know if making saved data is worth it

If a user has downloaded your game from the web, then the only way to keep their saved data is by copy-pasting the save files to the new version of the game, assuming your game saves all data locally on the same folder. Alternatively, if your game saves data somewhere on the user’s files outside of the game’s folder, then newly downloaded versions of your game can detect it.

If a user is using the Itch app, and you used “Butler” to update your game, users should be able to update without losing any data generated by the game itself.

If you are not using “Butler” but instead manually uploading each new build and removing old ones, I’m not sure. I wouldn’t be surprised if saved data are not saved in this case.

Hope that helps.