Is there anything I can do to help prevent CRF in senior kitties?

I have two spayed female cats in their late teens who are healthy now, but I like to be proactive. I saw a friend's cat die of CHF and it wasn't pretty. They eat Wysong Uretic kibble (without it Tigger will invariably get a UTI) as well as some raw organic grain-free frozen pre-made food called Paw Naturaw, premium grain free organic canned cat food, and some homecooked wild fish and other raw or cooked organic grass-fed meats (i do a homemade organic grainfree mostly raw diet for my dog and give them anything out of what she's eating that they want) they also get extra taurine and lcarnitine for their hearts, as well as a gut health mix of prebiotics, probiotics and enzymes (to prevent their touchy tummies acting up) as well as salmon oil with coq10 and 1 ml organic apple cider vinegar for arthritis. tigger also gets turmeric for her joints. One week a month they get milk thistle to keep their livers clean and they get dried organic parsley blended into their raw/canned mix to assist kidney function. I also give them bottled water only, and in a mug to encourage drinking, since they seem to like it better than a bowl. I also blend water into their raw/canned mixture until it's a soupy consistancy. What else can I do?