This past weekend at Ad Astra, I attended a workshop by Robert Sawyer. He talked about the importance of coming up with the high concept or log line during the planning phase. I already have a draft (and rewrites) of Mysterious Paris, but this has energized me with ways to fix the novel.
I took my original concept and have tweaked it slightly: When your parents betray your ideals, is there anyone you can trust?
This gives me a lot better idea about what to prune, what to add, and what to look for in the remaining scenes. This might still turn out to be novella, but that's OK, if I'm satisfied with the new story.