Once you pass transit security and reach the departure level, there is no direct route back to arrivals. You will need some one to escort you down to the arrivals level. Though there have been reports of this happening, expect it to be rather difficult if notnmost likely impossible. If I were you, I would get a shower and a snack in the arrivals lounge and head in to Tokyo after that.

Trains to Tokyo station (Narita Express) run every 30 minutes most parts of the day, and take just below an hour. You shosho be able to get some hours wandering around Tokyo before heading back. The Japan Forum has plenty of threads discussing options and possibilities for a short Tokyo visiv.