Yes, if you got 60% in CBSE board, you can appear for improvement exams in all subjects next year. If you improve your marks and meet the eligibility (75% overall or top 20 percentile in your board), you can give JEE Advanced again—but only if it's your second attempt and you appeared for JEE Main the same year. JEE Advanced allows only two attempts in two consecutive years after Class 12. So yes, it's possible—just plan carefully and study well!