If you're on PC it should keep your save file automatically when you start up 0.7, I've never had an issue with my saves being gone when changing versions
Copy the last save of 0.6, found in the Tio Cass --> eternum.tiocass folder, and paste it into the folder in documents --> Ixalon --> com.caribdis.eternum and then into the sync folder. I did that and started from the old save
