If you want to repeat a year before going to the college entrance examination, then repeat the third year of high school. If you ask for a tutor, you should consider your family situation. The tuition fee for tutoring is not small. You can find someone who can really help you. Personally, it is unrealistic to ask a tutor.
According to you, I don't know if I can pass the present grades. I guess I missed too many cultural classes. After one year of repetition, your total score may increase by 100, but you are less likely to be admitted to a good university, and you may be admitted to an ordinary college.
I think it is more realistic for you to consider vocational training schools, where you can learn a skill and find a job after graduation.