Generally, the way to upgrade SmarterMail is as follows:
1. Back up your installation
2. Stop the SmarterMail service
3. Uninstall SmarterMail
4. Run the installation of the latest Build (or whichever Build you're upgrading to)
5. Verify your site and the SmarterMail service are both running. These should start automatically after the installation finishes, but it's good to "trust but verify"
Now, people do various versions of this, but it's the recommended way to do an upgrade.
Oh, and a straight upgrade from 9575 to 9714 should be fine. I'd just recommend you review the release notes for all releases between those 2 versions so you know what to expect, paying attention to any highlighted changes/features.