Just do a lot of rollbacks.
There's two types though. My favorite for sucking a horse back is more of a reiner/cowhorse approach. Stopping, drawing the horse backwards, and then rolling back into the fence, lope off, stop, suck back, rollback over the hocks.
After a little more of that we'll do the second type of rollback. Which is basically run down the fence, and then turn into it. No stopping involved. Just sit, turn into the fence, drive out.