For web maps and apps in Portal and ArcGIS Online, it would be great if you could take a published map/app and work on a v2 if it in a draft state. Once ready to go live, publish the new version, replacing the existing. Currently the only way to create an updated version would be to start with a copy and make your changes. Once done, because its a new item, there's a new URL that you then need to replace anywhere where you had links to the original map/app.