by Stephanie CrosbyNon-stop service between Louisville and Denver resumed today from Frontier Airlines.Frontier Vice-President of Strategy Daniel Shurz says they had to cancel the flight in 2008 because the company was struggling in bankruptcy.“We knew we had a lot of passengers that wanted us to come back to this route," says Shurz, "and what we saw was that demand in the market had held up well. We do see changes in markets over time and we have to keep an eye on that as well.”Frontier Airlines was purchased in August by Republic Airways Holdings, and announced last week a new partnership with Midwest Airlines.