You will not lose any of your recorded shows, even if the Tivo has cable cards changed. You just need to re-run guided setup when your new cable is installed and if any cable cards are needed/changed.
Series 2 (PLS, sold)
TiVo HD 1TB (157 HD Hrs, PLS, "652")
Roamio! Oh, wait, Its Juliet!
The TiVo Apocalypse begins on Sat 2013 Feb 16 00:00 GMT!