https://www.reddit.com/r/UkraineRussiaReport/comments/1q1c211
I dont have the translation but this video (1:40) shows that the Arena is still being developed and it looks like they plan on putting a ammo box for the APS on the side of the tank. I always felt that APS had a too few of a ammo capacity to deal with the amount of FPS's we see now. Even Hedgehog styles of tanks take dozens and dozens of drones to destroy which is the high end of the amount of drones a tank may experience. During the early parts of the war I think the number was probably around a dozen or so.
APS in general don't tend to have many charges in them, if they are reloadable at all in the first place. Only the latest versions of Trophy can reload and it only holds 3 charges per launcher, Iron Fist only have two charges por launcher and have to be reloaded by hand, if I remember correctly.
Its a matter of trade-offs what you want to prioritize; adding more charges and a reload mechanism means more complexity and weight which forces you to instead reduce the number of launchers to compensate. Fixed casette launchers are simpler but you need more of them to cover a given area from multiple angles, and so on.
At the end of the day, the best way is a combination of APS, Jammers and properly designed cope cages.