I'm not an expert on reviving a plant like this, but I'd probably just take cuttings and try and root them and re-plant the whole thing anew. I did read in Southern Living last night to cut back 1/3 impatiens and petunias in July as they get leggy. Not sure what our experts will say about doing that though.
-Nan

It could use repotting maybe and some feeding. You could also cut some stems and start cuttings like Nan said. Put it in a cool spot with some morning sun. With some feeding you should get some new grow at the nodes and cutting back a few stem will help stimulate that.

Thanks...I took both Nan's and Mr Impatiens advice...keep your fingers crossed!