What I suggest will allow you to start "fresh". You will be overwriting the version of ZC you have installed and replacing it with 1.3.7. If you follow the steps I outlined, you will retain all your data (customers, orders, etc).

DO NOT simply upload 1.3.7 to your live site and run the installer. That will wipe your database and you'll lose everything.

The site in my sig went from 1.2.7 to 1.3.7 without losing any data. There isn't anything 1.2.7 left to the site. It could just as easily be a clean install.