Add Menu to Unity Roguelike Example

I play a little bit with the 2D Roguelike Asset from Unity. I added an own scene for a main menu. Now if I start the game to this menu the game starts at day 1 and then go further to day 3 and skips day 2. I am not sure what causes this problem. I think it has something to do with the

 static private void OnSceneLoaded(Scene arg0, LoadSceneMode arg1)
 {
     instance.level++;
     instance.InitGame();

 }

is ther some workaround for this? I thought about reloading the game in another way, but I have no good idea for it. Thanks in advance!

Best regards