To be honest, even if you did all the things mentioned nothing is going to increase inactivity. It's because no one is actually active on this forum, it's just leechers. Like what I mentioned before, to get this forum active I believe you'd have to remove most of the leaks & leechers and only limit the leaks and become more of general discussion forum.
Then advertise. Like, why would I come to this forum to talk when I can go to another one that is 100% more active than this one, and actually get a reply to a thread instead of waiting days for one.