I've had the WordPress.com and Jetpack stats running on my site for nearly two years now, and it's always worked great.
Recently I started a new blog on a subdomain, as a separate WordPress install, and I of course added Jetpack to the site. Connecting to WordPress.com after activating was smooth and easy, as usual.
Going back to the main site, I got an 'invalid token' error on the stats page. It was suggested that I disconnect/reconnect from WordPress.com, which I did. After reconnecting, the stats history is gone, and has started over from zero...
I logged into my WordPress.com account to try to reconnect, but I don't see a way to re-connect my stats history to the current domain.