You can read this as a general idea.
It will be easier if you use hard disk that is able to connect to both server, and that hard disk will store the data as a bridge between both the server to sync the data faster since only deltas will be transferred.
Online: Run backup database task, sync blob from online local with hard disk.
Offline: Restore database, sync blob from hard disk to offline local.
Make it into a script and automate the process.