To migrate DH1 data to DH2, you need both app installed in the same system.
When you uninstall DH2, make sure you do a complete uninstall by checking the box that says “remove all player’s and database data”. After uninstalling DH2, reinstall using a new installer and at first launch, DH2 will detect the DH1 in your system and prompt you to migrate your data. click import and wait for it to finish.
If you are still not seeing the prompt, you may not have DH1 installed on your system or did not do a complete uninstall of DH2. Use “Revo uninstaller” to uninstall DH2 then try again.