Currently, heavy cavalry charge into a battle, break their lance charge out and magic up a new lance a few seconds later. I am not a fan of this behaviour. I feel it makes heavy cav hard to balance and leads to knights being a superior raiding unit thanks to burst damage when light cavalry should be the best raiding unit.
So instead of having magic respawning lancers, make it so heavy cav has to garrison in a building, or maybe go near a building, for a while to get their lances back. A charge would be an actual timing attack you must hold off for until needed rather than something to use as often as possible to get the most value.
Then some nations can get squires in the castle age, Squires would be a light cav target a random heavy cav near them and slowly respawn their lance, meaning that you can invest into mixing squires with your heavy cav in order to make them more useful away from base