i have to start a new game every update does anyone know why?
Hmmm.
The original versions of the Introduction, Chapter 1, Chapter 2 and Chapter 3 were written using a game engine called Visual Novel Maker. It tended to be a bit crap and all sorts of bugs happened. It could be that with each new version of each of those... the save games weren't shared.
With Chapter 3... after a lot of feedback from players... the author swapped from VNM to RenPy... Obviously, those two different game engines use entirely different save files... so maybe it was that?
But both the new version of Chapter 3 and Chapter 4 were in RenPy... using the same save file directory... so you shouldn't have needed to restart. The only thing I can imagine is that you hadn't noticed the RenPy rewrite and only played the VNM version of ch3.
I know Chapter 4 has been rewritten recently, after the author got slapped by Patreon for including content that it decided was against it's terms and conditions (or more realistically, to keep in PayPal's good graces). But that is still in RenPy, using the same save folder and none of the underlying data has changed... so that should be fine. (It hasn't been seen here on F95 yet).
It should be pretty easy to tell if you've been playing the RenPy versions... the main menu is completely different and the game stopped using a handwriting style font. If in doubt, head back up to the original post and download Chapter 4 (which includes all other chapters). Unless you've already played through chapter 4... in which case... chapter 5 will probably arrive in anything from 2 to 4 weeks from now (depending on how much time the author lost to the Patreon sanitized rewrite).