UK to Shanghai, then cruise to Japan, then back to Shanghai for flight back to UK

UK passport holder? Then you do not need a visa as you are covered by the 144h visa free transit for the two stays in Shanghai.

Thank you for the reply.
To be exact, we will fly into Shanghai and stay there for 3 nights. Then we'll be on a cruise to Japan for 7 nights which returns to Shanghai, where we'll stay for 1 more night before flying back to the UK.
That's a total of 4 nights in Shanghai, and we're entering, leaving, and then re-entering China.
Are we still covered by the 144 hour rule and definitely do not need visas...?
Thank you again.

Yes, you are definitely covered by the 144, just remember to book the tickets leaving China before you enter China, and the hotel reservation for nights' stay.