Reformatting will cause you to lose a hell of a lot more data than just shshs. Maybe you should be investigating that before performing such a destructive action on your computer?????????
As far as the shshs, Cydia may have them. Why not turn on your phone and see? Or why don't you just backup the files yourself with tiny?
When you use TU to save SHSH's, it saves them locally on your HD as well as requests Cydia server to save them. Sometimes Cydia's server takes a while before it saves your SHSH's but you can always open up Cydia and check which ones it has saved. As far as the local copy goes, unless you back those SHSH's up, you'll lose them with the format, but you'll still have the ones Cydia saved. I'd make a local backup for security if i were you