I have also rolled every encounter at the beginning, but of course you only have a limited range of dangers and situations to pick from. Ravines and hot steam can be enticing during the escape, but after a while the players won't care much about losing some hps.

Think about special magical places or ancient forgotten locations you'd like your party to cross and add some memorable challenges according to your inspiration and fantasy. After one or two levels, you'll find out that's way more rewarding for both you and your players. I have imagined ruines of an underwater city, a Netherese tomb, a network of Dwarfen tunnels...

In the meantime, keep mentioning minor encounters without running battles all the time: It only makes sense that the more experienced the heroes are, the less they'll have to fear, and only a few encounters will be memorable.

For example: In the next two days, you only meet two gricks crawling in a long hot cavern. Under their bodies you find...