I was in a hard battle and used all my spells (beside discarding) And now I got no more cards to use!
How can I continue?
Is it common, no. However, it will occasionally happen, especially on boss fights that aren't going very well. A strategy I use, is I make a deck that has approx. 30 cards or more for tough boss fights that I am doing solo (using almost every available card drawn in some fashion). If you are a minion owning class, they are most helpful in those situations. I keep a small deck for all other fights, including boss fights with any amount of group members (10 or less cards).
The above strategy is a way to prevent using training points or treasure cards to obtain the "Reshuffle" spell. As previous posters have indicated, "Reshuffle" can give you back your entire deck after exhausted, but I find that card more beneficial in small decks to reuse the same desired cards, more often.
Finally, as mentioned, there is no current way to continue if cards are exhausted. Your choices are really to flee or hope another wizard joins your battle to finish the fight, before the enemy gets you!
I did that once and discarded both my reshuffles. My life minion ended up killing the guy for me. Plus, if you are low it will start using your treasure cards. Needless to say, I don't discard my reshuffles anymore.
