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.