Plotting the Second Half

Halfway through:
But what's on the dark side?

I've burnt up the first half of my WIP at a rate I'd never imagined possible during NaNoWriMo. But just as I'm about to reach what I've plotted as the low point (the worst that could happen) I feel myself getting nervous about what's to come.

In the plotting workshop I took in September, we talked about how the halfway point of a novel can be the place where your main character hits bottom. Hits it so hard you can hear the thud a hundred miles. Just after that point, your MC realizes she has to change. Something she's doing isn't working. She figures that out. Once she does, she's on an upswing, piling up small victories and realizing new strengths, until the novel's climax (the battle of the book.)

Fine so far, but how do you keep tension in your novel when your character is racking up the smaller victories, and those leading to larger ones, and it looks like all is well?