Usually they come out quarterly, assuming there are new guns on the roster. We're about due for one cause last one was Sept 2015, but they skip some if no guns are submitted in that interval. I bet you'll see another one by April-ish.
That said, honestly, the stupid ****ing roster isn't worth worrying about anyways. It doesn't determine whether or not you can buy/transfer/import something, the dealers are the final arbiters of that regardless of what the roster says. You're better off spending resources searching for what you want (and/or how to get it) than frothing over a roster that's pretty much meaningless to you as a consumer.
-Mike