A Microsoft file hosting and synchronization service.
Hi Ben,
It is not feasible to extend expiration date for the shared link which has already been created. We need to recreate a sharing link for the document with an extended expiration date.
We suggest posting the idea in OneDrive for business UserVoice to submit your feature request. Providing your feedback is the best way to better our products and services for you and others.
Regards,
Joanne