No, you do not need to re-register for the IGNOU program if you have already paid the fees for all semesters but could not appear for the exams. Your registration for the program remains valid for the entire duration of the program.
However, you need to ensure that you fulfil the minimum attendance requirements, submit your assignments on time, and appear for the term-end exams to complete the program successfully. If you fail to fulfil any of these requirements, your registration for the program may be cancelled by IGNOU.
If you could not appear for the term-end exams in any semester, you can choose to appear for the exams in the next available session by filling out the examination form and paying the required fees. IGNOU conducts term-end exams twice a year, in June and December, and you can choose to appear for the exams in the next available session.
It is always better to contact the IGNOU regional centre or visit their website for more information and guidance on the process of appearing for the term-end exams and other academic requirements.