If an APN cert expires it in a sense severs the connection between your endpoints and Jamf Now. The device records don't disappear but any changes made to configuration profiles or inventory updates will no longer process. The devices themselves will happily continue working with the exception of Self Service. Jamf Now is an MDM only service(I think) so you may lose access to that.
Long story short, yes you will need to re-enroll everything. macOS is easier to re-enroll without a drive wipe, but it's a tricky process. iPad, iPhone, Apple TV will need to be wiped no matter what.
