Re registration in ca final

No, The Validation is done Every 5 Years.

Initial registration for Final Course is valid for 5 years.

Each Revalidation shall be valid for 5 years.

For Example:-

Students, who have registered for the Final Course on or before 31 st December, 2008 (including shifted students of Final (Old) Course to Final (New) Course) are required to revalidate their Final Course registration. Such students are advised to apply for revalidation before 31st December, 2013 without paying revalidation fee. In case any student fails to apply for revalidation by 31st December, 2013 he/ she then shall have to pay the prescribed revalidation fee, as stated above, after 1st January, 2014 for revalidating the registration.

In your case the registration is valid till 31st August 2016, so no need for revalidation as the registration period holds good for a period of 5 years.