The only way to renew your expiring Green Card is to file Form I-90, Application to Replace Permanent Resident Card. In the meantime, if you need confirmation of your status so that you can work or travel, you can make an appointment with your local USCIS field office through Infopass to get a temporary I-551 stamp on your passport until your new card arrives. This temporary proof of status is good for one year and that’s good since it may take that long to receive your new Green Card.
Now, if you are a conditional permanent resident who has a two-year green card and your Green Card is about to expire, DO NOT use Form I-90 to renew your expiring Green Card. In that case, you are required to file a petition to remove those conditions within 90 days of your card expiring by filing Form I-751, Petition to Remove Conditions on Residence. If your conditional status was based on a marriage, you must also file Form I-751.