If by former glory you mean having more than a dozen posters, the solution is fairly simple, if not entirely practical.
Every member would simply post on the bethesda/obsidian forums as much as possible, contribute relevant posts, preferably with information and/or insights that people find meaningful, and simply keep a link to this site in the signature with something insinuating that this is a fallout site....which, well, it sort of isn't anymore.
The thing is, the internet has enough "Post whatever, we're all just people" forums. Too many, really. The reason the UV was so successful in the first place was, even though other stuff was posted, we were a fallout message board. There was common ground that drew everybody together, and the off-topic posts were just an extension of the people who posted here and joined *because* it was a fallout site.