1130 is a fairly blank frequency to the west. There are no stations on the frequency in Illinois or Missouri.
But any increase would require a directional antenna to protect:
WISN in Milwaukee
WEDI outside Cincinnati (Daytime-only)
WOFC in Murray, KY
So, Emmis might be able to build a 4 tower directional array to send more power due west down I-70, but I think you would be very optimistic if you thought WFNF could get 5kW days and 1kW nights. Note the above does not consider any adjacent station protections, so the pattern might need to be tighter