Well... It seems that your clan isn't quite that well versed in what happens in the wilderness.

You're kind of usually supposed to use spare items so you don't lose all of your best stuff. Personally, I'm not surprised that a lot of people are leaving, because it makes it seem like it's the clan's fault that their stuff is gone. Seeing as they didn't know that they'd lose it all, and the clan itself declared war... They're probably pretty annoyed that war was declared in the first place, now.
What can you do to get them back...
Well, short of pleading, that is... Personally, I would try to contact all of them (you have no forums, right?) by email, IM, etc. I would try to get the message out that the clan is
not dead, and that you're organizing a rebuilding project to benefit everyone. Did every single member in your clan lose most of their stuff? If not... well, it's always good to organize a rebuilding effort, with wealthier members pitching in some stuff, and other members working a bit for gp, weapons and armor to contribute, and then distributing it out fairly evenly.
I'm no Cspace, but I think that it could work that way