I am an avid user of OsmAnd. Some of the maps I have are now becoming a bit outdated - shops that changed name, paths that no longer exist, new paths that are not yet marked.
How can I update a map that I already have on my system?
You can simply download/update your maps from within the app :
You'll need an Internet connexion for that. Also, be wary that maps can easily be hundreds of MiB (https://en.wikipedia.org/wiki/Binary_prefix) in size.