So you've already been donating and it's still high? I think you can donate about every 6 weeks.......and that's what I would suggest. That's what I do to try and keep mine down and it's working for now.
Have you ever been able to lower it? Maybe a one time phlebotomy and then regular donations after? Sorry bro.....I'm just trying to think how to fix this quickly, as I realize the seriousness of your situation.
As far as lifestyle? Not sure what exactly you do now.....but weights 5 days a week and 20 min of cardio every day cures almost everything but cancer

And the diet needs to be bland and boring. Boneless skinless chicken, white fish, eggs......broccoli, green beans ,peas........Brown rice, yams, plain oatmeal. At least 1 to 1.5 gallons of water every day. This is the cookie cutter cure all diet and exercise plan.
The cleaner and more boring your food......the thinner your blood. The more hydrated you are.....the thinner your blood.
Maybe you are already doing these things. If so.....perhaps meds are the only way. Either way , get this worked out bro. Stroke and heart attack become high risk if that number gets high.
Please let us know what ends up working for you. Perhaps someone else can learn from your experience.
God bless