I have no chant, or spell to offer. But I do understand what you are going through. Part of the problem is the simple fact that what you are studying does not hold your interest. You read, and even understand the words. But you are only going through the motions. Quite common, actually. I am pretty sure that if you look back at your last study time, you were reading the words, while thinking about something else. But that is easy to fix.
It has been said that increasing your knowledge is like filling yourself with the Goddess and God. They are knowledgeable, and wise. So as you gain knowledge, you gain a part of Them.
First, keep in mind, all the knowledge and wisdom that the Goddess and God have. Just as the energy in you is the same that is in Them; so it the knowledge They have.
Get relaxed, and cast a simple circle. Nothing elaborate. All you are doing is creating your space where you can balance yourself, then study. Casting a circle puts a sphere of energy around you. This will keep out distractions. Also, it will raise power to help you pay attention, and remember. Ask the Goddess to help you understand and remember. Once you feel balanced, stay in your circle and read away.
When you are done, thank all that were in attendance, open your circle, and enjoy the new knowledge.
As for a chant, I think a heart felt "I need help" would do more than any rhyme, or practiced verse.
Hope this helps.
May the Goddess be my light of knowledge,
May the God teach me to hunt for that light.