1. Inactives.
So you say that various members have gone missing? Never fear, the Justice League of the Internet is on the job. Assuming this isn't another one of Dr Yams' attempts to gather subjects for his hybrid EoFF member creations*, I would start by trying to contact the members directly. Years ago, colleague and eternal newbie Captain Chocobo sent a massive email to all missing members. The result was a glorious day where many forgotten heroes of the golden age came back to join us for one more mission**. It may be time to do that yet again. However, I would not stop there. Usually those members only show up for a couple days, post in a general spam thread, then go back on their way. We must compel them to stay. Now, I'm not suggesting we use mind control to make them turn on their fellow members, like my arch nemesis Grammar Nazi once tried on my sidekick and ward, Backspace Boy***. However, I do think we should make this attempt when we are doing a large scale event, much like the elections! Or publicize our other events such as Eyes on Plays, when we contact these forgotten friends.
Of course, some people just outgrow the days of magic and superheroes and will never come back to it. Losing comrades you care about is hard, I know this all too well****. When that happens, we will never forget the memories we have, but we must move on into a new era (WIN THE FUTURE--FOR GREAT JUSTICE!). Naw, I'm kidding. The JLI will drag these members back kicking and screaming, or be deleted trying!
Alternatively, we can just make this place as awesome as we can so that nobody ever wants to leave.
*see Super Delete Adventures #463: Dr Yams' Ultimate Sandwich
**see Justice League of the Internet #200: A Present from the Past
***see The Spamtastic Super Delete #135: Backspace Boy's Perfect Prose?
****see Justice League of the Internet #75: Lightning_Demon's Shocking Fate