Hello Pavithra,

For renewal you should go to a stamp wender in your district or tehsil court along with your old obc certificate . He should give you all the documents needed and after that you should go to your concern tehsil office. The tehsildar should issue your Renewed caste certificate.

Coming on the point yes you can apply to the exam but first go through the exam notification if there are any changes made there.Also caste certificate is issued for caste verification which is lifetime so that wont make a problem .While writing exam it wont make a problem but when you qualify the exam you need a renewed caste certificate in hands.