Idea Summary
Features can be installed during application creation by selecting Use Create App Wizard then selecting which features should be installed. They can also be installed after application creation by selecting the application, then under Tasks select Add Feature Page. But after installation, the components of the feature are never updated unless done manually.

To update the feature you need to remove the components and delete it from Application XXX > Shared Components > Build Options, then reinstall the feature using the steps above. This requires many clicks and page numbers will likely change during this process.  

Use Case
After an APEX upgrade, the components that are part of the feature may be out of date, using deprecated APEX functionality, and presenting errors in the APEX Advisor. Being able to update these features with the click of a button would resolve these issues and reduce the amount of manual work required.

Preferred Solution
Features should be upgradable with the click on a button just like the Universal Theme. After upgrading to a new version of APEX, when you go to your application, a banner appears along the top letting you know that a new version of the Universal Theme is available. By clicking the Refresh Theme button, it updates all the components of the Universal Theme to the version that matches that version of APEX. 

Features should have a similar button to update the components after an APEX upgrade.