Hi Carlos;
The only way I know is to manually refactor the old code first in PB Classic and get this a s clean as possible in that IDE. Then - and only then - begin the migration to PB.Net for the least amount of trouble converting to WPF/C# that PB.Nt uses.
PS: Run the PB 12.x "Migration Assistant" First on your old application and see what it recommends that you clean-up.
Good luck!
Regards ... Chris