This is mostly a suggestion for Lionesses, as Kings have a different functionality when it comes to leveling up.

When you level up your King, you get some new stats! However, with Lionesses... you don't. Thus, this negates the reason to manually have to level them up as leveling a lioness serves no purpose in the game other than a numerical trophy of how much you've hunted with that particular lion. A Lioness will collect stats by hunting, not by leveling up such as a King.

So, my proposal is just to remove manual level-ups from Lionesses in general. This will reduce the amount of clicks, refreshing, reloading, and scrolling you have to do on each page. Since a Lioness can only collect stats from hunting (or other items? I've never tried a Giant Tortoise on a Lioness :P) it might be convenient to have level-up notices on the hunting page itself.