hi Patrick,
Not very advisable, but since its your custom transaction, you could do a bit of small hack.
Export the flavor, and change the program (from old to new) in there.
Import it back.
(Make sure you create create a copy of your original flavor, just as a back up)
Needless to say, you would have to be careful while doing it. But worth a try.
Regards,
Sushant