Automatic sensitivity label on existing labeled documents and emails

If I enable today automatic sensitivity labeling for label "Confidential" on behalf on sensitive information type "Credit Card" and 1000 documents are labeled with the label "Confidential". What happend if I remove the sensitive information type "Credit Card" from the label "Confidential", and put it on the Automatic sensitivity label "Highly Confidential". What happend to the 1000 documents which already have the label "Confidential"? Will it be modified to "Highly Confidential" or not?