Currently we can only gain rewards offline or for a brief moment when clearing a new floors. For an Arpg gaining items in real time is key. I few suggestions to help with this could be some of the following:
Add a chance to randomly encounter a "boss/mini boss" that drops appropriate items while being on an already cleared floor.
Add elite enemies to already cleared floors.
Allow "exploring with a higher drop rate" to always be active
Add a chance to encounter a portal monster that when killed warps you to a dungeon with random modifers.
Hourly, daily, weekly changes that gives rewards based on difficulty.
And on top of that, maybe add like difficulty. Easy, hard, hardcore, etc. Tougher floor, tougher mobs, greater loots.