Artificially Update Champions
A lot of the older champs seem incredibly outdated when compared to new or updated champs with their fancy recall animations and wide variety of quotes. Adding new quotes and animations to old champs would take a lot of time, you could they just have some of their already existing quotes and animations play when they buy/recall?
has a bowing idle animation that would work pretty well for a recall, and
's animation where he looks at his pennant and then the sky is perfect for a recall animation, just to name a couple.
can simply say "Yes..." or "Forged in pain!" for buying an item and his "The inferno begins" quote works for the start of game quotes that newer champs also have. Those are some examples of how older champs could be updated to make them seem newer and more up-to-date. I don't think that this would be too hard to do, although it might be time and resource consuming. Just something to consider.