After completion of 4 year need to re-regestration with icai by paying Rs. 400/=  (I Think, but not sure).

There is no limit for giving attempt ...If there is limit then nominal fees for Re-registration..

https://www.charteredclub.com/for-how-much-time-is-registration-to-ca-course-valid/

As per Institutes Accouncement dated June 23, 2011

https://220.227.161.86/23150periodannoun2.pdf

Period of Validation of Registration in Chartered Accountancy Course

CPT students: valid for 3 years.

PCC/IPCC students: valid for 4 years.

Final students: valid for 5 years.

BUT IT IS INFORMED THAT THE REFERRED ANNOUNCEMENT IS PUT ON HOLD TILL FURTHER CLARIFICATION/ ANNOUNCEMENT IN THE MATTER.

https://icai.org/new_post.html?post_id=7510