Lightroom :: Automatic Updating Of Files?

I am early in my learning curve on Lightroom. I understand that changes are not automatically applied to an image file but rather kept in a Lightroom database to preserve the original (non destructive). However, that is not a goal of mine. After making changes to a file or adding keywords, I want Lightroom to automatically update the actual files (in my case jpegs) so that I do not need to export them to be used elsewhere such as in a slideshows etc. I have found settings that imply the "metadata" is or can be updated, but I do not know if that is the "develop" changes I made or the keywords or if I need to do that every time before I close lightroom. Right now, I do an export of my entire folder of 20,000 images after each session where I make changes and then I use that export as a source for my automatic backup programs and supplies a continuous slideshow on another machine.

Maybe another way to say it is: after making changes and closing Lightroom, I want to be able to take an image from "My Pictures" folder (which contains all my images) and know it has the latest changes made and the latest keywords embedded. I do not want to have to export these files. first.