1) Click 'Abandoned Orders' under the 'Reports' heading of the 'Control Panel'.
2) Select 'Everything' from the first drop-down menu.
3 & 4) Search for your customer and click the 'Submit' button.
5) Scroll down & click the 'View' link of the abandoned order.
6) Click the 'Cart Reminders' tab
7) Click the 'Send Reminder' button or 'Send Another Reminder' button if this wasn't the first Cart Reminder.