I've been working on re-invites and wanted to share how I find them. I go to SEARCH in the upper right corner, then in the search box at the top I type a generic word like "beautiful" -- everyone who has ever had beautiful in their name will show up. Also click the box "Has Primary Photo" at the bottom, so you will have the correct ones for th achievement. I go to page #100 and you will find old old profiles, and you will work your way backwards - when done with everyone, go backwards to page #99, etc.
Go to each profile and you'll see the PINK re-invite box on the right. Click it - then you'll receive a a message at the top "Message Successfull Sent". I find sometimes you will STILL see the pink reinvite box after going through this process, but it SHOULD count.
Hope this helps you!