Usually the easiest way to add a renewal is to use the same deal and offer records. So you would just hover over the existing offer, click Funded (again), and enter the details of the renewal:
If you'd like to see separate offers, you can also hover over the submission and click "Add offer" to create a new offer, then mark that new offer as funded.
Or, if you'd like to see separate submissions, you can click the greyed out submit button (Mock Sub) to create a submission, then add an offer, and finally mark it as funded.
