You can only "update" apps by resubmitting them to Apple/Google, meaning, the apps stay the same unless you manually update them.  

What you can do though, is have an app that loads content from a URL that is updated by CMSB.  So for example, if you have a page called example.com/mobile/news.php or news.rss.php, you could load that into the app.

You might want to take a look at: http://phonegap.com/  Note that there's a lot of new technologies to learn to make that work.  

Hope that helps!

One of my clients, wants an app for Android and iOS. My question is this one: After I published the app in the google play store and the ios store, my client would be able to update the app via cms builder.

Thanks for your time