Hello!
Well, I think the best way is to remind people to come on and visit. That can be done by the mass e-mailing system that we have.
I will definetely do that some time soon, and hopefully people will post more and all! :)
I've been pondering this for my forums for the past year or more & other then an RPG in my CSI forum I had no more ideas. :(
I think the key is to keep it fresh. Remind people is good, through an email, just detailing the updates, even if it's tiny ones, like we've got a new banner or something. Ultimately it's down to the members, because you can't force them, and sometimes competitions and things get repetative, or make the forum apealing for a while, and then people never come back. If you've got a forum with substance, and a loyal band of members (god, I sound so tacky!) then ultimately, members stay.
My two cents! :D
I know i am only new here, but maybe a roleplay forum, based on criminal minds.