I've been down this road out of necessity before, and I don't recommend it. There is a lot of caching done in Tomcat so that it doesn't always have to reference the MySQL database. A restart is really the only way I've found to force it to reload. If you wait long enough, without again modifying the element, it will eventually expire the cache and go to the database. So, if the change isn't incredibly time sensitive, you could just wait.

Any way to, instead, use the API to do what you need rather than interacting with the database directly?

API just adds another layer of complexity.
I just encounter issues like, setting the value I need is not an option. So I have to go to modify the options.

When I'm working with a very large manifest, that's being used in many places, with many values. There can be allot of back and forth between options and values.

Now that I know its cache. I can try purging the cache on the OS. maybe there a purge option in tomcat.