what spells were they? you probably just need to rest and charge, not dispell. depending on the spell, if cast on yourself, a simple purification bath would do the trick. add some sea salt to a bath, visualize the water as a white light, as you wash it over yourself, visualize the white entering you and grey light being washed away.
if it's just energy you need, you could give it time, or while meditating visualize white/silver/gold/blue light entering you and feel the energy in your body.