London - Beijing - Tokyo - Shanghai - London (via Beijing)

Hi, I am preparing a flight from London to Beijing then from Beijing to Tokyo and from Tokyo to Shanghai and back to London via Beijing, all the flights would be on Air China. Do I qualify to use the 72 hour free transit in Beijing and 144 hour free transit in Shanghai considering I have a stopover in Beijing before I return to London (I’m not leaving the airport on the stopover) or do I need to get a multi entry visa?