A guru will always instruct us to purify our hearts by chanting. The scriptures say that the moment we chant the Holy Name, all the results of actions from our previous lives, which bind us to this material world, are destroyed.

 
य एतद् देवदेवस्य विष्णो: कर्माणि जन्म च ।
कीर्तयेच्छ्रद्धया मर्त्य: सर्वपापै: प्रमुच्यते ॥
 
ya etad deva-devasya viṣṇoḥ karmāṇi janma ca ।
kīrtayec chraddhayā martyaḥ sarva-pāpaiḥ pramucyate ॥
 
“One who chants the glories of Shri Krishn and his lilas is freed from all sins.” ( Shrimad Bhagwatam, 11.31.27)
 

If we are already purified by chanting once, what further purification are we carrying out by chanting again and again?

 
The purity that the scriptures are referring to is in fact separation. Even if we are saying his Name with love, unless we feel separation from him in our hearts, our chanting will not be fruitful. When we have a diamond, we do not always appreciate its value, but if it gets lost, we instantly realise the precious nature of what we had. Similarly, we may feel satisfied that Krishn is here with us in the form of our deities or  shilas. We may even live in Krishn’s homeland, Vrindavan. But it is only when we feel this separation that our emotions will be strong enough to attract his grace.