On my most recent playthrough,  I told Wynne to get lost after we killed Uldred. I remember her saying something to the effect of "If you change your mind, I'll be _____," which made me think I can pick her up again. I'd just load up a previous save, but it's long overwritten. 
Any help guys?

Never mind, I figured it out. Looks like, despite Wynne saying that I can find her again, she simply disappears. Luckily, I had a save file that I hadn't noticed.

You answered it yourself, but just to reinforce, no.  You can't recruit anyone again after they leave you or you tell them to leave.