While it is true that misrepresenting the facts about yourself when you apply for life insurance can result in the policy being invalidated, some errors will not. You should endeavor to keep the facts as accurate as possible, but something as simple as accidentally listing the wrong age is not usually one of them.
If you realize that you have made an error, contact your insurance provider as soon as possible to have the data corrected. If the mistake lists your age as being higher than it actually is your rates could go down, and if your age is actually higher than you have listed your rates could increase somewhat to reflect he risks associated with being older. By contacting the insurance company yourself, you have shown an act of good faith in coming forward with the corrected age, and most insurance companies will not penalize you for the error.
If the mistake is not caught until you pass away, there could be a deduction made against the policy before it is paid. This would happen if it turns out that your age was higher than you had listed on the insurance application. The reason for the deduction is because the insurance company will deduct an amount equal to what your premiums should have been based on your actual age. If your actual age turns out to be lower than you had stated, your family will not receive any additional money to make up for the overpayments, even though you have actually paid in more than a person of your age should have paid.
The fact is, if your insurance company does not discover the error during the contestability period specified in your policy, you probably do not have anything to worry about. After that period has elapsed, the insurance company is legally bound to honor the policy. They can adjust your premiums to reflect the actual risks and even dictate an amount that must be paid to bring the policy up to what it should have been, but once you have gotten past the contestability period there is little danger of the policy being invalidated.