It’s been a while since I played the game end-to-end but I feel like there was already a lot of content, it just was missing some bug fixes.
Personally, I think you should spent a bit of time patching the game and fixing bugs without changing the content much, then focus on a remake or new title, per options 2 or 3.
I like the idea of the game kind of being “locked” as it exists now so you always remember what your first project looked like, and focus on a fresh start for the future.