Since the PIO card was originally issued, if your passport has expired and if your PIO card is still valid, you can get a new passport number endorsed in the PIO card.

• San Francisco: Miscellaneous Services Form
  Washington DC: Endorsement Form
  
  All others: A cover letter requesting that you would like to get the new passport number endorsed in the PIO card.
  
  
• Copy of the surrender certificate.
  
  Appilcable only in case of naturalized citizens of Indian origin.
  
  If you don't have it (because there was no such rule when you earlier applied for PIO), you must get it first.
  
  
• Original PIO card with photocopy.
  
  
• Houston: notarized copy of the new passport.
  Chicago, New York: Original passports, both new and old, with photocopy.
  San Francisco: Original new passport and address proof.
  Washington DC: Notarized copy of first three and last two pages of old and new passport.
  
  
• Fees:
  Houston: $20
  Chicago: $0 (Zero) if the PIO card was originally issued by the same consulate. Otherwise, $10.
  New York: $0 (Zero)
  San Francisco: $20
  Washington DC: $20
  
  If applying by mail, additionally send $20 for returning mail charges.

Make sure that you send the documents by the means that you can track. Please write "Endorsement in PIO Card" on the top of the envelope.

If you apply in person, the service is rendered the same day.

Processing times vary if you apply by mail:
Houston: 7 to 10 days
Chicago: 15 to 20 days
Washington DC: 30 days

It is not mandatory to get the new passport endorsed in the PIO card. However, in that case, you will have to carry both the old and the new passports along with the PIO card to travel to India.