When he asked the demon to "make me like I was" I don't know that Spike intended to get his soul back, but I think deep down it's what he wanted...what he knew Buffy would want. Or perhaps another way to look at it is Spike didn't necessarily want the soul, but William did. The Spike part of him just wanted to be strong again. Which would fit into Angel's comment last night about Spike wanting the cup more. I think that observation was spot-on. Spike wanted the cup to get back at Angel, while William wanted the salvation it promised. I think Angel has always held back from pursuing what he really wants for fear that it would be selfish. He still sees his soul as a punishment for his past sins, part of him feels like he doesn't deserve to fulfill the prophecy.