update database between gnupg versions

Hello I"m having this problem: I have running a BIG system made few years ago and the programmer is not working anymore. The system store few data in mySQL database using gnupg encryption. All was fine until few days ago, when the key expired. So i generate a new one and all was perfect. But... The new gnugp key was generated under version 2.0.22 and the data stored in database is under gnugp 1.45 Then.. ALL new record is encrypted perfectly and appears in the database, but the archive of a LOT records are missing, because the system is not displaying the data encrypted with the old version. My questions : 1 - is possible to dwongrade the GNUGP version to 1.45 in the server using cpanel + cloudlinux and then, re-generate the key using the old 1.45 version? 2 - or is possible to update the entire database to read the encrypted data wit the new key generated under the new version? 3 - or i"m doing something wrong ??? Thanks Fabian