Clash Royale – How to Take Out the Barbarians Effectively

The "lost cards on upgrade" is an illusion. (Well, poor interface design, to be percise.)
The upgrade animation shows draining of all cards, but the extra cards are actually saved. If you have enought cards, you can even upgrade a card multiple times in a row.

You should feel free to upgrade your cards without a worry. (Other than spending too much gold.)

Start a list and see where it overlaps with this list. It may take a bit, but you should be able to find it out as soon as you hit one of the more rare chests, provided Supercell hasn't changed the order.