만료전이면 반납해야 되는 것 같내요. 만료후이면 상관없고요.
만료전 분실이면, 그렇게 사유를 적으라고 되어 있내요.
=> https://www.uscis.gov/sites/default/files/USCIS/Resources/B5en.pdf
Q) I have an old reentry permit. Do I need to turn in my old permit if I am filing for a new one?
A) Reentry permits cannot be extended. If your permit expires, you’ll need to apply for a new one. If you have a valid reentry permit in your possession, you will need to send it in when you apply for a new one. You need not send in an expired reentry permit. For security reasons, USCIS will not issue a new reentry permit to someone who already has a valid one in his or her possession. If you need a new reentry permit because your previous one was lost, stolen, or destroyed, please indicate this on your application for the new permit.