Setting the same Accept header at every request is not difficult or error-prone. But that aside, what happens when you store versioned resource URLs in the cli

Setting the same Accept header at every request is not difficult or error-prone. But that aside, what happens when you store versioned resource URLs in the client, and then you want to upgrade your client to a new version of the API? Do you just lose all of your data from the old version, since you don't have a single URL for a resource?