That's a great question! I apologize you were unable to see this option to automatically resend to contacts who did not open you email. This is a feature only available in our newest Third-Generation Editor, Newsletter Emails. I took a peek at your account and can see you are working in both our newest editor as well as our older Legacy Newsletter Emails.
At this time this feature is not available in these Legacy Newsletters. Instead I would suggest following these steps to resend your email to contacts on this campaign's did not open report.