You can request INS to provide an duplicate one.
You have to use INS-Form 102.. But one of my friend did that when he lost his passport while getting his H1-B extended.
I got this from INS Website :
How Do I Apply to Get a New Nonimmigrant Arrival - Departure Document?
If you are applying to replace a lost, stolen, or mutilated INS Form I-94 (Arrival-Departure Record) or Form I-95 (Crewman\'s Landing Permit), you must file INS Form I-102 (Application for Replacement/Initial Nonimmigrant Arrival - Departure Document). If the INS Form I-94 or Form I-95 is mutilated, attach the original form. If the INS Form I-94 or INS Form I-95 was lost or stolen, submit a copy of the original INS Form I-94. If you do not have a copy of your original INS Form I-94, please submit a copy of the biographic/photo page from your passport and a copy of the passport page that was stamped by immigration inspectors when you entered the country. If you cannot submit any evidence of your legal admission to the United States, please submit a full explanation and proof of your identity.
Hope this helps.
Thanks,
