So I had some time yesterday and decided to replay the whole game, making different choices than in my original game. I wanted to keep my current game as it is, though.
I had to saves (used only 2nd one, though), so I went to third (unused) save slot and pressed "start a new game". I wasn't taken to the beginning of EP 1, though - I was made to rewind game till the very beginning.
After some time, I checked save slots and realized my 2nd and main save was overwritten by the new game I started. There's no problem in me going through all the episodes again, but I regret not being able to resume my game with original choices I made once EP is available.
So, is it a bug or do you have to recite a magic spell to start a completely new game? :(