Bruce:
Fully paid: Do you mean by an actual payment or a credit note? Is the applied document future dated as well?
A quick fix is to run the next period end to a future date that captures the future dated transactions and the rerun it for the correct period end date (this use to work in older versions, you should test it on a copy of the data first).
Another option is to reverse all of the transactions using the exact same date as originally entered and the enter the transactions with the correct date.