The company is reportedly back in merger talks with Frontier.Merger talks between Frontier Group Holdings (ULCC 0.67%) and Spirit Airlines (SAVE 43.55%) are reportedly heating up again, and investors are excited about the possibility.Shares of Spirit soared as much as 50% at the open on Wednesday and traded up about 40% as of 11 a.m. ET.Third time's the charm?The future of Spirit Airlines has been up in the air for some time now. In 2022, the airline agreed to combine with Frontier but JetBlue Airways stepp ...