You're not alone! Yes, about a third of the way in is an incredibly common point to get stuck ... mostly because you've run out of story-telling fuel, I reckon. 25-30k seems to be about as much as any of us can reach on the initial tank, as it were, and then you need to have a pitstop.
I blogged about this stage here:
http://emmadarwin.typepad.com/thisitchofwriting/2011/07/the-30k-doldrums.html
I do think that even though reading-through on hard copy and getting to know it again is hugely useful, there's a risk that you then get lured inot detailed revising, and get caught in a loop of working and re-working what you've already done, rather than moving forwards. So my suggestion would always be to make notes on the script about what you
would do if you were revising, pin down any drastic changes of mind about what you've done, or what you intend to happen in the rest of the novel, but don't do them. To keep the momentum up, when you get to the end of the read-through, just write onwards as if you'd actually done those revisions.
And this is a post for later, about how to tackle the revisions:
http://emmadarwin.typepad.com/thisitchofwriting/2011/06/how-to-eat-an-elephant.html