First off.....there are probably 20 models/brands of RV's that have a 29M floorplan. You need to supply a little more info for better help with your issue.
Typically, these cables are run during construction and can't be easily replaced. You have two options....run a new cable through areas you can access, or use a wireless unit. I bought the wireless set up for a prior coach when the HDMI cable went bad. They're available on Amazon.