No, you don't have to replay the previous chapters. The changes made to them weren't too big. I'd say the most significant ones might have been the songs we added here and there.
That said, do keep in mind that only save files from 0.4.1 will work. After we release the original 0.4 we did a considerable overhaul in the code to fix some issues, but that sadly meant that save files from 0.1, 0.2, 0.3 and the original 0.4 no longer would work.
If you do need to remake your save file, I suggest you check the game's menu and enable "Skip Unseen Text" (or something like that, I don't have the game on hand to check.) Then you can click the Skip button (or press Tab) to blaze through the game in a few minutes. If you don't remember which choices to make you can check this Walkthrough we made.