Shania Twain has added 14 new dates to her Let’s Go! Las Vegas residency at Zappos Theater at Planet Hollywood Resort & Casino. Aug: 21, 22, 26, 28, 29 Sept: 2, 5, 6 Dec: 2, 4, 5, 9, 11, 12 Shania will serve as the creative director for the new shows, which feature her past…