In addition to its current double-daily Airbus 319 roundtrips, Frontier will be adding two more roundtrips with either 318s or 319s:

Source: Frontier Airlines Reinforces Capacity to Top Destinations and Prepares for the Start of New Subsidiary, Lynx Aviation=

This should really heighten the competition between DEN and OKC now, and while it might go the way of OKC-LAS, the press release says Frontier is adding this in its top performing markets to/from Denver.