Keeping Your Book Fresh When You Aren't Writing

On deck right now:
--Six articles to write
--6-8 storyboard scripts to complete
--One freelance book proofing project to wrap up
--One gratis article about the recent flood

I'm not listing this out to be a look-at-how-busy-I-am whine, because I think most writers and creative types end up with a lot going on. But it's more to point out that there's one thing missing on this list. Do you see it? Yeah. My book. Where is that?

Like the half bag of lettuce that got stuck in the back of the produce drawer, it's wilting beneath the other projects. Good projects. Needed projects. Welcome projects, even. But my favorite thing to do is work on that book, and time has not been in abundance.

So how can I ensure my manuscript stays fresh? How can I keep my characters from, as Stephen King put it, "going stale" until I can dive back into their world?

I once heard a writer say in an interview that if the only time you spend with your characters is when you face the written page, then you don't know them well enough. So, in the midst of other writing demands, I'm trying spend some time with my characters.

How would they react to the traffic I'm sitting in?
If I had lunch with one of them, what would it be like? What would they order?
At this time of year, what kind of clothes would they be wearing? Where would they shop?
Would they have let that man cut in front of them?

All kinds of little things. Frankly, when I get far away from my work in progress I start to forget sub-plots and the sequence of clues and timelines and all those other really important things that you shouldn't lose track of. Fortunately, I've got those written down for reference. But it's the voices of the characters I don't want to lose. So I try to spend time some quality time with them in my head until I get to sit down with them once again.

What do you do to keep a project fresh when you can't get to it?