Hello - I currently hold a 60 day M-Visa. I exited the country before my 60th day

and re-entered for another 30 days, for a total of 90 days in country this calendar year. is there a maximum number of days I can be in country with in a calendar year?

I am scheduled to return to China for work for 3 weeks in November, and want to confirm if I need to apply for a residency permit, or if there is a maximum number of days within a calendar year? I have never exceeded my 60-day duration on a single trip. Thank you!