It's because the dialog lines have been changed.
By default you can only skip line that you already seen previously. But it's not meant as "you've seen the line X of the file Y", nor as "you've seen the line X of the label Y". No, it's meant as "you've seen the line that contain all theses characters in this particular order and that is the line X of the label Y".
So, whatever if it's a change in the dialog line itself or just a spelling correction, you haven't seen this line and you can't skip it.
If you're talking about the "I need to rollback few times before being able to play", it's the natural behavior of Ren'py. The player saved at the line X of either the sleependversion label or of the endofversion one. And that's obviously where the game will load...
The best way to fix it is to not use the end.rpy file. Instead, put the ending code in a label that will later start the next day. By example, if this update ended at day5's night, the ending code would have been put in the day6mwakeup label. And, obviously, when you work on the next update, replace the ending code in this label, by the effective code in the game.
This time, Ren'py's behavior will serve you and not deserve you. Like it will not be able to find the exact line where the save happened, Ren'py will load at the start of the label. And also, don't split the label in two, to ensure that Ren'py will load correctly.