There aren't many options. The following are, according to the route map, states not currently served:
Idaho
Hawaii
Alabama
Mississippi
South Carolina
North Carolina
West Virginia
Maine
New Hampshire
Vermont
Massachusetts
Rhode Island
Connecticut
New Jersey
Delaware
I'm assuming that "new" means not ones that were cut in the past couple years, which would discount NJ, MA, CT (others?).
Hawaii would require significant work though, no? Both Flag Carrier status and ETOPS certification would be needed, similar to what Allegiant just had to go through.