As per the link below it's mentioned "
You have to clone the app and add new permissions. Then test your app in the sandbox to make sure it uses all the new and old permissions and meet the max error rate requirement."
However, as per I know once your app is in production, you cannot change anything.
You need to ask firstname.lastname@example.org for any help. Once they added the permission with your request(not sure if they do.. most probably they don't) you need to test again for that permission you acquired.
The official recommendation is to create a new app, add proper permissions and graduate it. So in that case you need to go through again.