You can now convert a backup into a snapshot. After it is a snapshot you can transfer it to any region you like and it will no longer auto-expire.
To do this just goto the images tab:
Click on the droplet where you have backups enabled and you will see a dropdown list of backups that were taken.
On the right will be an icon that will show a tooltip that it converts the backup to a snapshot.
Just click that and it will appear in your snapshots tab and you can then transfer it to any region from there.