It took a while for my prayers to stop being formulaic. Even when I was an agnostic, the rituals were hard to break. At the encouragement of a friend, I forced myself away from Christian phrases like, "Dear Heavenly Father" and "in Jesus' name." After a while, I was still praying, but my prayers were more honest.
"God, I don't know if you're there, but today sucked." I talked as though speaking to an imaginary friend. I dared Him to prove Himself, told Him I was disappointed in Him, said all the things the church taught me were rude or foolish.
Even as a Christian now, that hasn't changed. If God hadn't shown up for me, it still would have helped to talk out my feelings. As you're leaning toward atheism,
@Deidre, I recommend allowing yourself that freedom. Either God will respond or He won't, and at worst you'll develop a habit of talking to yourself, which can be like verbally journaling your thoughts.
Over time, I found my prayers became less frequent than when I'd prayed as a ritual. I don't call my friends up at the same time every day to tell them how I feel, and so it is with God. The more you force yourself to defy the ritual, the less you'll do it, until either God will show up or you'll stop talking to Him altogether.