Why not, instead of giving currants for every level up, give items instead?
These items could range from a bean, to a musicblock, to a "admit one" ticket, to emblems, to walloping big diamonds, to herbs, to bags, to awesome stew, plain crystals, loam...
This will make people wonder what will get at their next level up, instead of just a "eh, level up, get favor and currants, then continue"
When you level up, you need not get items all the time, sometimes it might be currants, or sometimes it might be buffs! So, say, when you reach level 5, you gain the "silvery-tongue charmer" buff instead of an item or currants. Or, maybe, upon hitting level 10, you gain the "extremely hallowed shrine powder" buff.
This could also be the answer to not getting currants after level 20.
Maybe:
Upon levelling up, give a choice of 3 items and allow selecting one?
Give a skill that increases the value of the item you get when you level up?
Vary the items per person? (they have to be ~about the same value, of course, not a pleasing amber VS an ruby)
Give the community the list of what you get every level? :D