The only time backups occur is when you exit Lightroom.
You could configure Lightroom to backup your catalog every time you exit, and use that as some sort of "manual backup"
Thanks, that's too bad, as that is how I have it configured currently, but I hate the nag screen. So I will play with the settings some more to see if I can find something I like better.
I like the fact that it will check and optimize your catalog file which is why I wish there was a simple manual operation for this.