1—Supreme Court has held that if renewal is applied for in time, the company is bound to renew as per rules. There is no scope for discretion. Usually, companies tend not to renew if a claim is made in the previous year. This is illegal.
2—Do not believe the insurance company when it says renewal is up to 70 years and is discretionary thereafter. There is no valid discretionary clause. You can check it by reading the policy bond / document / literature yourself. I do not think you will find such a clause there. Most companies state in their literature that coverage is till 75 or 80 years. Check from your own insurance papers and the company literature / web site as to what is the coverage age. If it is 80 years, forget whatever somebody verbally tells you.
3—If your company literature says maximum age is 75 years, it may be advisable to switch to a company covering till 80 years. If you switch, you might lose some benefits for no claim for 4 years.