If you want to engage in mathematical theory research and don't want to take too much risk, you can consider Beijing Normal University. The Institute of Mathematics of Chinese Academy of Sciences is also very good.
If you want to transfer to a technical major related to mathematics, you can choose one between Beihang University and Beihang University, and some information majors can take math classes directly.
If you are still hesitating, I suggest you directly consult our Shengshi Qingbei Education (see my ID) and give you some targeted suggestions.