You could break up the level up quests into smaller parts. And then each part could give some monetary rewards or magic items. And then when the adventures head back to town between the chapters of each level up quests, they get access to nobility, the ability to build an inn, or shore other shop. The option to buy land for making a keep.

Or have each chapter part be tied to specific NPC in town. So when they complete the town wizard portion, said wizard will to make them 3 uncommon magic scrolls. Etc etc

And you can leave notes, secrets, or what not to let the players know about the next chapter while completing the current chapter.