After a nearly hour-long search, which included visits to some five stationery stores, local resident Doris Kessler finally found the perfect birthday card for a friend yesterday at Woodfield Mall. 'This is just perfect for Kate!' said Kessler, 47, holding the card she selected for friend and co-worker Kate Adler. The card read, 'So you're 39... Again!' Said Kessler, 'I love to kid Kate about her ageshe'll never admit how old she is!' Kessler plans to present the card to Adler at work Thursday, along with a humorous 'Over the Hill' mylar balloon. 'She's just going to die when she sees that!' Kessler said. 