In all likelihood, your current lights are a 12 volt system DC system (battery system). Different from a house that has 120 volt AC power the runs the lights, outlets, and all other appliances. Again, when you plug in your RV to 120 volt AC, the RV converter converts the AC to 12 volt DC electricity. Your lights and light fixtures are 12 volt DC. However, your RV also has 120 volt AC power outlets (like in your house). Thus, you can plug in a house appliance such as a TV or blender to the 120 volt outlets.
What you can do is replace the 12 volt DC light fixtures with new 12 volt fixtures. The good news is that there are a lot of low cost 12 volt fixtures.
Check out these that I found on Amazon: https://smile.amazon.com/s?k=12+volt+light+fixtures&ref=nb_sb_noss