I have recently and with disappointment uncovered a thought/desire that I have been unsuccessful at "cast[ing] into the flames of love." It is bothering me — when I am happily reflecting on God or Guru as I am taking care of daily activities it will come in and bother me. What is the best way to take care of this nuisance? "I cast all my thoughts, desires, past karma into the flames of love. Make me whole, make me pure, make me one with thee."
The short answer is this: keep offering that thought into the flames of love, into the loving hands of the Guru.
Whatever this thought/desire you’ve uncovered is, it has probably taken lifetimes to develop it. We can’t really expect a few months of offering it to God to necessarily rid ourselves of these things with deep roots.
Swami Kriyananda gives great advice for when we stumble upon one of our faults. He said, "Be grateful. You’ve had this quality possibly for thousands of lives and you have been unaware of it. Now that you are finally aware of it, you can put out the energy to be free of it."
So, you might adopt that as your underlying attitude — gratitude that you are finally becoming aware of this thought/desire that is far from new.
Perhaps you could also adopt an attitude that is at once grateful, playful, and full of faith. For example, "Oh, there it is! Guruji! I’m giving this to you. I will continue to give it to you until you finally remove it entirely! Every time I offer it to you, the thought/desire becomes weaker in me. One day, it will be gone!"
Before sleep every night, offer your life into God’s hands, offer all deisres into that flame of love, and go to sleep focusing on your deep inner freedom.
Blessings on your quest for freedom!