Reusing your old leads will give you a chance to reach out again with a fresh copy and a different approach. Create a new campaign with a new subject line and move already contacted leads (you want to choose the status "Email open, no reply", or "No emails opened").
To reuse your leads, you may follow these procedures:
On your campaign dashboard, go to the Leads tab.
Choose a filter of your leads, based on the status.
Choose one filter at a time.
To select all the leads under the chosen filter, navigate 'Email open, No reply.'
Click on the checkbox and choose 'Select all in campaign (with filter)'
Click Move to open the drop-down menu and select 'To another campaign.'
Select the campaign you want to move to the leads or create a new one.
Note: Moving leads from one campaign to another will reset their campaign status and history. So only the data (variables) get copied, its status will not be copied.