It is possible to retrieve the BDM from the Production server.
Actually the BDM is a XML document stored inside the Database.
You can write a query to retrieve the BDM from the database.
The BDM is usually stored in the Schema DB.
Look for a table called Tenant_resource and the BDM is stored as client-bdm.zip.
Write a simple query to retrieve the BDM and then right click and download on to your server or your local computer.
Please make sure to perform this in Local environment or DEV/TEST before doing it on PROD.
Make sure the BDM is not removed from Database.
If that happens, Restart server and Push BDM from Portal again.