By chanting Hare Krishna, we certainly become free from all sinful reactions, but that does not mean that we deliberately commit sins and then counteract them by chanting.
There are many people who chant Ram Krishna Hari, but are also, unfortunately, addicted to some bad habits. Their chanting of Ram Krishna Hari is good but that is not leading to transformation of their hearts. Why? Because just chanting of Ram Krishna Hari is not enough. When we chant the names of the God, it is as if we are taking medicine.