Can I do overtime with current employer for meeting minimum salary requirement for ILR

Hi,
I am going to be eligible for applying ILR in June 2020. Minimum salary requirement for ILR next year is £36,200. I am currently getting £32,800.
My contractual working hours per week are 37.5
Can I work extra hours with the same employer (who has sponsored my Visa) to meet the minimum salary requirement?
If yes, than how many hours extra i can work? For working extra hours, do we have to change anything in the certificate of sponsorship?

Regards,
Sani