As long as you were forthcoming about smoking on your life insurance application and told the truth, your life insurance policy will stay intact.
If you ever allow the life insurance policy to lapse, for instance, due to not paying your premiums on time, you will need to get a new life insurance policy at smoker's rates.
Your life insurance policy would not be reinstated at non-smoker rates.
However if you convert your current term life insurance policy into a permanent life insurance policy someday, that will also be at non-smoker rate.