Menus are like sharks—they need to keep moving or die. And among all of the moving parts that make up a restaurant, one of the most important is the need to constantly evolve and keep menus fresh and on-trend to drive frequency.This is especially true of older, well-established brands. Concepts like IHOP, TGI Friday’s and Burger King are beloved features of the dining-out landscape, with iconic signature dishes they could never take off the menu (Pancakes! Potato skins! The Whopper!). All menus need to be updated and kept current, but for legacy brands in particular it is imperative that brand continuity be balanced with new signature items that attract new customers and bring back regulars to try something else.Look at IHOP’s new Bakery Favorites, an LTO (limited time offering) that features such over-the-top fancies as Red Velvet crepes and pancakes, sprinkle-topped Cupcake Pancakes, and decadent Cinnamon Swirl Brioche French Toast. These new specialties are smart-smart-smart: Pancakes and French toast are familiar products to IHOP’s core customer base—we’re not talking about something unknown or unintimidating here, after all—but they’re also on trend and just a little daring, with that sophisticated touch of using brioche for the toast.TGI Friday’s latest initiative is lunch, with a new menu sporting such specialties as a Truffle Stacked Burger, Mediterranean Mahi Mahi Naan’Wich, and a slew of nonalcoholic signature drinks (Cherry Limeade Slush, anyone?), which are high-profit rather than high-proof. An “On The Double” express-lunch pairing allows customers to choose from mozzarella sticks, house salad, Caesar salad or soup, along with selected lunch-sized entrées, priced at $6.99 to $8.99. Quite different for a chain that launched as a Happy Hour oriented casual pub.And what about Burger King, which has recently been promoting hot dogs, chicken nuggets and now new Chicken Fries Rings? “Take a Break from Boredom” says the company, and these items are certainly pushing the envelope without causing Burger King to turn its back on the burger that brought it to the party. The Grilled Dogs became permanent within a year. And now it would seem that BK is also in the chicken business. The Chicken Fries platform has been successful in every iteration (Buffalo, jalapeno, Fiery) since it was first introduced, in 2005, and the core product has also become part of the permanent menu. The new Rings may sound crazy (whatever happened to the consumer’s growing appetite for real, unprocessed foods?), but there’s no denying that they’re perfect for kids and fun for adults as well, especially the ones behind the wheel.Dunkin’ Donuts is another legacy brand that is not afraid of reinventing itself through the menu. The company’s recent test of Chicken and Waffles is only the latest salvo in the donut chain’s battle to stay relevant against other QSRs that are crowding in on breakfast, like McDonald’s and Taco Bell. For years Dunkin’ has also been pushing hard into the lunch and snack sectors, with sandwiches like Texas Toast Grilled Cheese and Snack ‘N Go wraps, also rejuvenating Coolattas and smoothies.And then there’s Cheesecake Factory, going on 40 years in business with a menu that’s still constantly evolving—Skinnylicious, Super Foods, trendy new items like Avocado Toast, Blood Orange Mojitos, and a pizza topped with bacon, dates and blue cheese.There are important lessons to be learned from all of these brands, whether yours is also a legacy or is brand new to the marketplace. Menus are living, breathing, evolving entities—because so are guests and their tastes.Burger King Grilled Dogs photo credit: theimpulsivebuylicense CC by SA 2.0