If you really want to keep using Royal Snakes, then you will need to use either Resurrection or Sacrifice. You should find Sacrifice around somewhere. You can get yourself a stack of something weak (eg Peasants) and go into an easy fight with a view to replacing the Peasants with Royal Snakes.
I think everyone acknowledges how good Royal Snakes are in the early game, but I think you'll find that there are tons of useful units to be found, especially in Ellinia (hint hint)
