Accidently Unsubscribed Contacts from CRM API Import

We are in the process integrating our CRM with Constant Contact. In the process of importing contacts from our CRM to Constant Contact to a new list, a large number of contacts were 'unsubscribed' in the process by accident. We went to the recent activity page and exported the file of the people who were unsubscribed, and we have tried re-uploading the file with Email Status 'Active', however, nothing has changed. Is there any way to revert changes or mass change the 'Email Status' using imports?