Upgrading Password Safe version 1.x to 2.x merely consists of opening the database with the newly installed version. The conversion takes place on the fly and a backup copy of the version 1.x file is created the first time the coverted databases is saved.
Use the backup file created by Password Safe during the upgrade or convert your current database to the 1.x format (File > Export To and select Old (1.x) format...) .