One thing you should know before making any decision is to identify your career goal. If management is your choice, opt for it. You can continue the same because DU JAT requires a dedicated preparation for 3 months maximum.
It is suggested that you can keep yourself aware of current affairs, start reading newspapers for vocabulary enhancement, interact more on social media regarding DU JAT and analyze the previous year's trends.
Try doing your biochemistry studies as well as the preparation of DU JAT side by side for at least one hour daily. It is definitely a hectic process but it ultimately pays off.