If you need more life insurance coverage, you may be able to add additional coverage through your life insurance company.
If you feel rates are much lower now, and changing carriers may offer you more life insurance coverage at a lower cost, this may be a reason to replace your policy.
However, before making any changes to an existing term life policy, make sure you have your new term life insurance plan "In Force". That means, the new policy has been underwritten and approved, and you have been accepted for the new life insurance policy and paid your first premium, so you have the new life insurance coverage before you cancel an existing term life policy.
If you feel their are better rates available you may want to compare rates and then ask your existing life insurance company or agent for a re-rate consideration. Maybe they will lower your rate if you have quit smoking, lost weight, or are a healthier person than you were when you originally applied for your existing term life insurance policy.
The first step is to compare term life insurance rates online to find out which companies may offer you a better rate on the same type of term life policy you currently have, and make sure you are comparing apples-to-apples, for instance, comparing 10, 15, 20 or 30 year level term life insurance policies.