I Would "Experiment"
Before making any adjustments, I'd get the bore as clean as possible, then fire 1 Cold Bore Shot at 100 yds.
Whether or not it was still 3" high, let the Bore completely cool, and without cleaning, fire 1 more Cold Bore Shot.
I'd want to see if there is any change in that 1st shot, with a clean bore VS. 1 fouling shot through.
You already know that You'll get a 3" high hit with a cold, fouled barrel. Try that 1st one when it's clean. Then, if You get the same result, I'd do what the above Posts suggest. Adjust to Split the Difference.
If You get a good shot (or 2 or 3) after it's clean, then clean and prepare everything else for Your hunt.
Rifles can be very "funny" (for lack of a better term). I have a .270 Win. with a Custom Barrel, and it does not like 130 grain bullets. 90 grain, 110 grain and 150 grain bullets... That rifle shoots all of them like a Champ. But out of all of the 130's I have, Barnes XFB, Sierra MatchKing (135) and Hornady Interbond, those all shoot the same, no matter what I do. Through ALL of my development trials, they've all been consistent at 1 1/4" to 1 1/2". All 130's.
But my first reaction to Your dilemma, would be to get the bore clean first, go through a little more process, before I adjusted. Then, if everything stayed the same as it is now, go ahead and adjust.