I haven't fully worked it out yet, but my traffic has been fluctuating quite a lot recently, and I think it is partly dependent on how active I am. I've been busy moving house the last couple of weeks (and still only have slow mobile internet at new house) so haven't been on much and my hub views have halved. It happened this way a few weeks before when I'd been inactive and then rebounded. I'm waiting to see if it rebounds again when I'm back to active duty, I really hope it does.
So hang in there, keep writing hubs, asking and answering questions and commenting - your fall in traffic may just be temporary, and even if not hard work can restore it.