Legend 5: Fighting against dragon more than one day?

Hi! I'm sorry, maybe there was a question like this before, but I can't use search in German
If you defeat the dragon 2 rounds (he lost 2 cards) and then go to sleep. What happens when you try to fight againt at the next day? We need to win just 3 rounds, or each new battle with dragon all the cards must be reshuffled?
Thank you for answers!

If you defeat the dragon 2 rounds (he lost 2 cards) and then go to sleep. What happens when you try to fight againt at the next day? We need to win just 3 rounds, or each new battle with dragon all the cards must be reshuffled?
Thank you for answers!