Repeating El Nath PQ?

All you have to do is make sure that you leave through the top portal before the timer reaches 0.

You just answered your own question. I went about 6 times with a DK because Dragon Breath wouldn't drop so he just kept ignoring whenever Stance dropped. Even if it dropped there's something you get after beating it, you just have to drop it and you can enter again.

Stance is NOT a drop.