Digital BW, The Print

If I'm not sure how long til I print next (weeks to a month), what's 
the best way to maintain nozzles and not loose ink? Oh and is it 
better to leave it on or off?
I have a 2200 with K7 inks. I let it sit for a month and half without 
printing and the inks got sucked dry on a few cartridges.
That gets a bit expensive.....

Scott