Darwin Australia to Shenzhen

Hi, I'm and Australian Citizen traveling to Shenzhen directly from Darwin (Donghai Air), I believe I can get VOA for 5 days on entry however if I go to Hong kong for 5- 7 days can I reapply for another VOA on the way back abiding I travel via the stations that do VOA ? I had planned on booking a return flight

I will ensure I bring proof of hotel bookings in Hong kong before entering or would I be best to travel another way home.

Thanks

John.