If you plan to stay outside of the U.S. for more than one year but less than two years in duration, a reentry permit is needed for readmission. You must be physically present in the U.S. when you file the application (Form I-131). A reentry permit may be sent to a U.S. Embassy or consulate abroad for you to pick up, if you request it when you file your application.
To check the status of your re-entry permit application with USCIS, see here.
To check if the Embassy/Consulate-General has received your re-entry permit, you should submit this form.