For me, it was product development and design. I started writing code in middle school, and I really loved it. I pursued computer science in college, and while I did graduate with my b.s. in c.s., it was during college that I hit a similar slump. Over time, I realized it wasn't writing code that I was passionate about. In high school, I had to write code to implement product designs and different ideas that I wanted to innovate on. Programming was a means to what I was actually interested in. Now, I work developing products (not code), and designing UI's, and I love it. It took me a while to figure out that this is actually what I love, but once I figured it out, I was always in love with what I do. (Not just in love with what I do when it happens to be plugged in to what my strength, unbeknownst to me, actually was.)
I urge you, and anyone else hitting the same slump every now and then with writing code to think about when writing code is actually fun. What sets those times apart? When is it most enjoyable? Is there a pattern? Is it when you are also doing the design? Coming up with new features? Leading a team? Designing a developer tool or API?
Your strength and passion may lie elsewhere, and going through this thought exercise may help you uncover it.
Of course, I could be totally wrong; your situation may be completely different. Feel free to get in touch if you want to bounce around a bit of conversation surrounding this. My email's in my profile.