Well, looks like the flight situation is limited--an 07:55 from SHA (Hongqiao) to HFE, and a 22:30 from PVG to HFE. Reverse HFE 08:10 to PVG and HFE 20:50 to SHA.

Might indeed be a job for the train, at least there are more options for timing and by the time you figure in the additional non-flight time (getting to/from airport plus waiting time for check-in, baggage, security at each end) the train journey is about as fast. The fastest available are the D trains leaving from Shanghai Hongqiao Station, can get you to Hefei in about 3+ to 4 hours depending on exact train. Same in reverse. Except that to get from rail station to PVG, you'll have to deal with subway, bus, or taxi. There are other recent threads on this forum dealing specifically with options, prices, time frames for getting to/from PVG-City so search for them. Then you'll be able to judge when you need to leave Hefei in order to make your PVG flight.