You can create snapshot of your droplet in region A and then spin up a new instance in region B by specifying the snapshot you just created. Snapshots are available globally so you should be able to use it to clone droplets cross region. At least that is what I did in my setup. However, I am still new to Digital Ocean so there might be some other ways to do so.
Here is the article from Digital Ocean talking about Snapshots and Backups and a quote from this article about what I just mentioned: