I've hit upon a plot twist in my story that, while essential to the telling, will require me to take some extra time to complete this second draft. The challenge I was faced with was creating not only a compelling antagonist, but also strengthening the internal conflict faced by my protagonist. This new twist solves both of those problems, in addition to bringing certain plot elements in the rest of the story into focus. In retrospect, I feel foolish for not reaching this twist earlier. It was the obvious one, but I neglected it due to my desire to keep certain plot elements a secret until late in the story. By executing the twist and pushing a major revelation forward in the story, I am allowing myself to develop a different type of dramatic tension, while also strengthening my protagonist's arc. But sometimes I guess you need to realize what's not working and why before you can accept an alternative approach.
So now the story continues, albeit slowly. My pace has slipped. I devoted a lot of time in recent weeks to the GMAT (with spectacular results), but couldn't spend much time writing as a result. Now, with a bit more time on my hands, I'll hopefully get rolling again.