Once a subscription it is fully cancelled, there's no way to add payment to it.

You can only update billing if you have an active subscription. To re-gain access, you can sign back up to rejoin the group.

If your subscription is pending cancellation (ie still within the billing period), you can regain access through your customer portal.

Subscriptions to your particular group are subject to the groups terms and conditions. LaunchPass does not control group pricing. Please contact the group owner directly with any pricing inquiries.