It's difficult to be able to give full advice here as there is a bit of info missing.
There could be 2 components to the joint life policy, critical illness cover and life cover on an either/or basis.
If the policy had the same critical illness amount as the life cover, the policy would be finished as it would be payable on a first claim basis.
If the policy had double cover, the premium usually decreases by the amount of the now paid out benefit of the serious illness cover - I know of 3 insurance companies off hand that would treat the policy as such.
I think it would be wise to have a broker check it out for you because option 3 is not always the best option because you most likely are 2, 7 or 12 years older now than when you first took out your policy.
Patrick