@username The passport renewal service has been resumed.
@suggestions You can get the appointment for biometrics by filling a form online. However you need to go in person to get the biometrics done and your picture taken. Also don't forget to bring the money order in person and not send it to the embassy.

https://us.nepalembassy.gov.np/passport/

This link has all the information regarding the documents you need to bring, how you can make an appointment for the biometrics and everything.