Hey Bud,
I'm pretty sure that if you don't update a suspended subscription with new credit card information, but simply submit an update request either using the API or from within the Merchant Interface, that the subscription status will change to active. I'm not 100% positive though and am trying to track down that answer for you. I'll update this post when I do find out.
Just some additional info that may be helpful though--a subscription will only be suspended if the first payment in a subscription with that payment information is declined. So if you set up a new subscription, and the first payment declines, the subscription will be suspended. But if you have already had succesful payments in a subscription, then any subsequent declined payments will not suspend the subscription. It will continue to process as scheduled.
The only exception to that is if you've recently updated the payment information. If you have a subscription that has monthly payments, and the first four payments process normally, you then update the billing information with a new card, and the next payment after that declines, then the subcription will be suspended. But if you never update the payment information and a payment declines anytime after the first payment, your subscription shouldn't be suspended.
So if for some reason, updating a suspended subscription without new information doesn't make it active again, you could just cancel the old subscription and create a new one as previously discussed.
Hope that makes sense!
Thanks,
Michelle