Can a porcelain crown be reused after a second root canal?

As long as the existing crown did not break or have recurrent decay there is a possibility that you can keep it.  I would take the recommendation of your dentist.  Good luck.  

Hi:Depending on the fit of the crown, there is a possibility the crown can be reused if there is no damage to the porcelain during the root canal procedure.Best,Dr. Maddahi

Hello,
No, it's not recommended to use the same porcelain crown after a root canal treatment.
Dr. Franco
DentArtist Clinic