Just play the first 7 days. You don't need to survive all the 7 days, just make sure you play all the 7 days before you decide to not continue. Basicly what happens in the game is even thou it's random witch area you start on it always cycles throu all 7 arenas by day 7 and then starts over agein.
Just for the sake of being clear I got this playing on Default. Lost all my lives several times before day 7. I choose continue and keapt playing till i got to about level 24, but got it on day 7. So i guess "in the same game" means "as long as you keep continuing the same game" in this game.