Destroy them carefully and use the opportunity to create new ones with QR codes on them with your full public key (or just the full fingerprint).

I've written software to help me create QR codes for my business card, including PGP, address, web site etc. There are many gotchas, some apps ignore some VCard fields, hence it puts copies into generic comment fields, too. Seems to work OK now. Maybe I should turn this into a web service.

https://github.com/pflanze/vcard-scm