Seoul - Beijing - Amsterdam

Hello! I will be flying to China next month and returning in May after a 2-month stay. I have purchased a return ticket AMS-PEK and I only got a single entry visa.
During my last week there I'd like to visit South-Korea with a friend. Will I be able to use the 72-hour free transit to enter China again for another 72 hours, as my return flight will be departing from Beijing? The itinerary would then be Seoul - Beijing - Amsterdam.