First of all, anything released under CC-By-SA is under "full copyright". I suppose that you mean you want to release the revised version under some less permissive license, possibly one with no permission to others to copy the work.
You do not need to retitle your work (although you can if you choose to). To avoid confusion, you might want to change the web site to say something like:
The text of the original version of [book title], dated [date] including all chapters within it, is released under a Creative Commons Attribution-ShareAlike 4.0 International (CC-BY-SA) license. The revised version, dated [date 2] is not available under that license, but is instead released under [terms].
You might want to include a copyright notice on the revised version along with a notice that this is a revised version, and is not available under the CC license used on the original version.
You might prefer to take down the original version, and remove the release notion from the web site. While people who obtained the original under the CC-BY-SA license continue to have the right to redistribute it under that license (and to make derivative works, if the ND clause was not included) You are not required to continue to distribute the released work, or to advertise your previous release. You could replace the release notice with a statement that you had released the original, but are now distributing the revised version by a different method.
If you plan to publish the revised version with a traditional publisher, they will probably insist on you taking down any previous versions, and you will probably want to do this ASAP.
