How can I as an EB-5 applicant renew my re-entry permit outside of the U.S.?

This is not possible typically. Only possible option is to contact the U.S. consulate and see what they might approve.

You have to be in the U.S. to file a reentry permit, and you have to also be here for the biometrics which takes a few weeks ordinarily.

Need to do biometrics in the U.S. first.

You cannot renew your reentry permit outside of the United States. You can obtain a transportation/boarding letter or an SB-1 returning resident visa from the U.S. embassy or consulate in your home country. You should check the embassy website for instructions about how to apply. If you return to the United States, you can apply for a reentry permit, but you do not have to wait for the processing time; you do have to complete biometrics in the United States, but then you can return to Japan and wait for the reentry permit to be mailed to your U.S. address. Someone then will have to courier it to you so you can use it for travel to return to the United States.

Please contact the local U.S. consulate in your country as there are specific guidelines on how to renew or extend your stay while you are abroad. Also, due to the Covid pandemic, there have been expanded guidelines allowing permanent residence to renew their travel documents. Each consulate has specific rules. Good luck!

You cannot. Try returning through a third country which is not under quarantine like Mexico.