An A&P with Nicopress tool can do the job for you. I recommend 1/8" 7X 18 galvanized. Make the new cables the exact length as the old because cable length will change the angle of the rudder pedals and both cables must be the same exact length too. May want to solder or glue a puller string or wire to the old before pulling them out.Make forward end thimbles & sleeves and mark exact total length of rear fittings. Pull new cables in, the spring on the rudder pedals will pull them full forward and this allows sufficient cable extending out the rear to allow Nicopress tool. If rudder pedals don't assume the same neutral, you may have to twist the longer cable a bit to bring both pedals to neutral with rudder neutral (increase the twist, don't un-wind the cable). Lubricating the cables is not recommended, but I have seen some cable guide tubes that are not straight and light lubrication in deeded to reduce rudder pedal input force.
Have fun,
JJ