1. Pray while you study
You are bringing the word of God to people who need to hear it. You are not studying to fill their heads, but to change their lives.
As God's word reveals truths to you, truths your group needs to hear, take a moment and pray those words over them. Pick out one or two members per verse and pray that they would be convicted as they ought.
Build this practice into a larger system of prayer for your group. Brian Croft, who blogs over at practicalshepherding.com, wrote about a prayer calendar that reminds him to pray for every member of his church each month. It's great advice and you would do well to implement something like this for your small group.
Do a little bit of preparation each day and make this part of that system. You'll pray for each member of your small group each (week?) month and you'll be praying that each lesson touches their life in the exact way it needs to.
2. Change the way you do your devotions
I've always struggled with getting too intellectual during my quiet times. "If you're parsing Greek participles, you might be pushing it too far," at least that's what I've always said. Of course, God works in the midst of parsed participles--he gave them to us in his word. What I'm saying is sometimes I'm more interested in the intellectual pursuit than I am in feeding on the Word of God.
To combat this, I've begun praying through the Psalms. Professor Don Whitney gave an incredible lecture series [MP3 / PDF] on this topic some time ago. I'm not exaggerating when I say these lectures have had a profound impact on my life.
Take some time first thing to pray through a Psalm. Once you are done with that, only then start to take some time to prep your lesson.
3. Change your expectations
Just as in a marriage, not everything can be newer, better, and awesomer every day. Pastor Doug Wilson preached a sermon series on the spiritual disciplines. When he discussed Bible reading, he likened it to breakfast. We all love steak and eggs for breakfast, but that doesn't mean we're going to have it every morning.
Some days you are going to roll out of bed and eat a bowl of Cheerios before heading off to work or school. That's ok. Nobody wants to eat Cheerios for breakfast every day. But when that's what you get, you should still be thankful for the food in your stomach.
It's possible that the dryness you are feeling is unrelated to your small group preparation. I would still try to pray through a Psalm in the morning, but don't freak out if your subjective experience during your devotions goes through some swings. It's natural.
4. Separate your devotions from your prep work
Finally, you may need to decide that you don't get to "double-dip." I know some pastors that wouldn't dream of preaching a sermon that they hadn't been prepping during their quiet times all week. I know others that said if they did that, they would burn out quickly because they would be too busy turning their work into a sermon instead of being changed by the word of God.
Teaching a small group involves more sacrifice than most people assume when they sign up. You may need to sacrifice and find time in the afternoon or evening to prepare, separate from your morning quiet time.
What about you? Have you had this problem before? What did you do? Which suggestion resonates with you the most? Post your answer in the comments.