If it isn't rg-6 already , you might try taping the 2 ends together with electrical tape and after disconnecting the other end. Try pulling the old wire out with the new one attached. But most likely the old cable/wire is secured along its path and won't pull out.
I had to run a new rg-6 from the external connection in the water service bay to the switch over box above the dash. I just ran it along the frame within the other wire bundles then up thru the dash, behind the a pillar trim and into the cabinet. Works fine and is a single run cable with no connections to work loose as I travel down the highway.
Dan Sees, Full Timing in the MH & Part timing in a S&B In Hampstead, NC
2013 Winnebago Journey 42e, 2014 Featherlite Car Hauler 3110 17.5', 2008 Mazda MX5,
2008 Toyota FJ Cruiser