Keeping Games Alive

I've noticed that I don't do so well keeping games I'm GMing very alive. I believe it comes down to trusting that players who become a bit inactive are just away for a short term, which negatively affects the game, and then it snowballs into a dead game.

How much do you all advertise your game? Do you keep a list of backup players who've expressed interest to call in if things start to slow down? PbP is a favorite medium of mine and I'm always looking to get better as a gamer/GM, and this is an area I've noticed I need some improvement.

Thoughts?

I posted before that a technique that works for me (when I remember to do it), when a game seems to have drug inexplicably to a halt, is to restate the situation, list any options the characters brought forth, and ask the PCs to jump in.

It may be that the simple reminder from the GM is enough, but sometimes I think the players can end up with different understandings of what is going on, or what to do next, leaving some to just wait and see what the others do. Then a week goes by.

That's good advice, thanks. With PbP moving as slow as it does, a reminder of the situation and options is something I do appreciate as a player, but haven't internalized as a GM.