Multiple visa

I am flying London to Tokyo and then back again next month with a stop in Shanghai Pudong on both the outbound and inbound flight. Both of these stops are about a 20 hour layover. I obviously want to leave the airport on both occasions and explore Shanghai, but was wondering if you can get the 24 hour visa multiple times within such a short period.
The flights are 10 days apart. Any help is very much appreciated!