If you are a schoolmaster, you can make it in time. There are some big names in history. After three months of review, I can be admitted to Tsinghua Peking University. Besides, you still have a year, which is totally in time.

If you are an ordinary person, it's too late. Changing subjects in senior three means that you have to start over and spend a lot of energy to learn new subjects. After one year, you will have to learn new subjects and review English and Chinese. It's really too late. Unless you are gifted, it is really not recommended to get back to the topic.