The constant struggle between "I should revisit my old favorites" and "i have so many books on my to-read shelf!" I definitely think it's worth it to reread, especially if you had your first go at it when you were really young. I think it's also important to know when to stop reading! I've wasted WAY more time stubbornly trying to finish a book just to say I did than revisiting a book I loved.
It's so hard. It takes multiple reading to truly appreciate a book and all of its nuances. But I usually succumb to the anxiety that I won't get to read all of the books I want to in my lifetime. Most of the time I've re-read a book it's been for a class and I found it very rewarding. But I can't remember the last time I re-read one at my own behest.