If you are medical / non med student and If you are preparing for any competitive exam like neet which is based on 11 th syllabus you should repeat your class.  But if you are not intersted to give such exam and want to do job or anything then 12 marks are only important. No need to repeat 11th.moreover if you are preparing for any exam you can drop one year after 12 and then prepare for 11 . Repeat it only if it affects your future goals and you will that you will study harder otherwise it is waste of time