Repetition can make magic happen: repeat a word or a phrase enough times and it breathes new life, fresh meaning. Or repetition can strip language until all that's left are empty rhythms and sounds. Words are funny like that. Noah Haidle's 'Birthday Candles,' which opened on Broadway Sunday night at the American Airlines Theater, tries to build poignancy and depth through moments that repeat like a record needle stuck in a groove. Instead, this Roundabout Theater Company production gets caught in a superficial cycle of wannabe profundities and emotional pantomimes.