There are a couple of solutions.
If your TV has an HDMI input there are devices that send HDMI over coax but a bit pricey. About $200 for one transmitter and one receiver.
If the existing cables are for component video there are devices that convert HDMI to component video. This requires 5 cables. Three for video and two for stereo audio. About $50 for the converter.
There are also wireless devices available. About $250 for one transmitter and one receiver.
The simplest and cheapest solution would be to run an HDMI cable from sat receiver to TV.