My dog is a 2yr old BC. He is fit and active - you could even say he is often too busy to sit down and eat

He has a diet of JWB, some royal canin dental biscuits, with 1-2 weekly sardines in oil or tomato sauce, 2-3 scrambled egg added, with occasional tins - butchers, nature diet, winalot. He is on Fit N Fertile, and Yumega.
He could do with adding around 2kg to get to a showable weight. How can I do this slowly and healthily?