I don't cleanse my cards and I don't tell them anything. They're tools, like a knife and fork at dinner. The need for a change of attitude is within you, that's all. If you want to use your cards differently, then just use them differently. The struggle, if any, will be in your mindset and your habitual way of reading with them.
I think too many people give their personal power away to the cards. The only real power is within the reader. The cards are not able to see, think, feel or do anything apart from the person putting them to use.
All matter is energy, as that old rule goes that we're taught in school. And of course, that's true. A rock is energy but the atoms of a rock move so slowly that we think of it as a solid object. The atoms in water move around more easily so their energy is more fluid. And fire's atoms are moving so fast that the energy they transmit is hot. So in one respect, you could say that your cards do have some energy because all matter is energy, but they don't have personality, powers of their own, spirits attached to them, or anything more than your roll of paper towels has. All the supposed benefits of putting crystals on them, putting them in the moonlight, attempting to cleanse them in various ways are mostly in the user's mind. That's a powerful thing, though. Your mind and your beliefs can actually make miracles happen, but always be aware that the power is yours, it isn't in the cards. The power is what you believe and manifest by means of using this deck of cardboard and ink. You may not think that's important, but it's extremely important in how effective you'll be as a reader.
I don't mean to sound preachy, but once in awhile I do just feel like I have something to contribute that bears consideration about this and I can't help myself.
If you love using crystals, moonlight, cleansing rituals or whatever else, don't stop doing them but also give some thought to where the power of those things really comes from. You and your spiritual power are strong and miraculous and in your hands, your cards become the avenue for that spiritual energy to manifest itself.