Cloning would be the cheapest way to resurrect a character. Resurrecting Vader would undermine EVERYTHING we see at the end of ROTJ. His death scene and last words would mean NOTHING if through some convenient plot device he is brought back. It is just...I don't even want to think about it. If that happens, the next time I will watch ROTJ at the end: Luke: [...] I've come to save you! Vader: You already have...Luke. You were right, you were right about me. Tell your sister... Me: Oh shut up already! You'll get resurrected in a few years.