Whell, When I posted my first fic here about a years ago, a few people read it. Then they stopped. Or at least stopped replying. I posted, and waited. What I am trying to say is that you shoud post new chapters whenever you feel like it. Because, at least for me, whenever I waited, the topic died out, and I'd have to repost the damn thing again.
Try posting, like, a chapter a week, and see what happens. Mybe they just have no comment at this time, or just haven't seen it.