[AndyPharmc]

But they didn't ban your whole account, did they? PErhaps you can keep that chat site, put some other ads such as those who pay by CPM, have some common affiliate programs such as diet and chatting up girls, that kind of ebooks.. Since you have the chat site with adsense for 6 years, you know what kind of ads were displayed by adsense, so try to find affiliate programs related to that, or contact directly some advertizers which were regularly on your chat site for direct ad selling, etc..
But then you can also send traffic from your chat site to your other sites with a big banner.
It should be a site that is related to your audience on the chat site, so that you'll quickly acquire traffic to this new site.

It is part of the game I think, like in simcity when you have a natural catastrophic event which wipes out big part of your city. Or anything similar in a strategy game. Does it mean you're giving up? Or build something even better on the freed up space? up to you.