By renewing your policy timely, you can avail the benefits of coverage provided without any procrastination. If you got late then you have to wait for 30 days to get off the coverage.
Another benefit that is added to your insurance on renewal is 5% of No Claim Bonus (NCB) if you haven't registered any claim on each renewal.
Some coverages like maternity and critical illness have a waiting time of 4 years. If you haven't applied for up-to-date renewal, then the waiting period begins again with the scratch.