You can definitely repeat your 12th standard (Science stream) in India even though you have already passed.  Check with your old school's administration about their policy on re-enrolling students who have already passed 12th Science.  They might have specific procedures or deadlines for applications.

If your previous school doesn't allow re-enrollment, you can explore other schools offering Science in the 12th standard. They might have their own admission process for repeaters.

• Your 10th standard mark sheet
• Your 12th standard mark sheet (though you passed)
• Transfer Certificate (if changing schools)
• Migration Certificate (if changing boards) - only applicable if switching educational boards
• Passport-sized photographs
  
  
  I hope it helps!