Sure (and I wouldn't bother wasting any energy at all contemplating the lounge issue; if you want a shower, go to the Ramada). The Maglev will take you to Longyang Road, where you can transfer to the #2 metro line and go to Lujiazui (the aquarium is really nice) or NJ Rd. Assuming you get a boarding pass for your onward flight, you can safely get back to the airport 40 minutes before departure, but I'd allow 50 minutes travel time for the trip back because, even though the Maglev only takes 8 minutes, the subway takes up to 20 minutes and the Maglev operates 3x per hour.