I don't know if everyone is compulsively driven to re-read the books they love, but chances are that if you loved something once, you'll still love it, or at least some part of it. Until you get to the point you can recite the entire thing by memory, re-reading lets you re-live that first moment you began to realize you were reading something really special. Especially if you've just read something that left you disinterested, you'll be amazed at how good it feels to read something great.
But, also, to re-read while I'm reading something for the first time; to go back to passages that seem elusive or mysterious, or are thornily dense with hidden meanings. While I tend to gobble my way as quickly as I can, there's something to be said for stopping to smell the sentences.
Take more notes:
It always feels sacrilegious to scribble in the margin of a book (like defiling the skin of some holy text), but like dreams, the brilliant insights you think you had while reading Kafka will soon disappear into the labyrinthine hoarder's lair that is the brain. I'm not saying you should write in your books. I'm saying post-it notes work just as well (and now, you can re-evaluate your old ideas once you've sobered up from the reader's high).
Read outside of your comfort zone:
Try to read, from time to time, a book you think you won't like. Sometimes, you'll have changed your mind.
And, more generally, be more creative in your selection process. Take unlikely recommendations. Spend more time in physical bookstores wandering slowly from rack to rack until you've gathered a stack. Spend more time in libraries. Find out what your favorite writers are reading (because they're probably reading a lot).
Read complete sets:
Though it's more daunting with D.H. Lawrence than J.D. Salinger, there's no reason not to read the entire life's work of an author you worship. Even the failures, absurdities and oddities will charm, in their own way.
No wasted opportunities:
It's very easy to spend 3 hours surfing the Internet without really thinking about it. And it's hard to cut yourself off from the world when your phone seems to track your movements. But there isn't all that much time in the day to read -- so use it. And, when you have an entire day or night with nothing to do, consider letting yourself have the chance to read for as long as you want, the way you used to.
Evangelize more aggressively:
If you tell a friend enough times that they should read something, they will eventually read it.
Read what makes you happy:
Disregard the above. When you're alone with a book, you can do whatever you want, as long as you enjoy it.