Śrīla Prabhupāda Says

Regarding how our business is to become Kṛṣṇa conscious in this very lifetime

Devotee: Prabhupāda, I heard it said that the spiritual master will always come back until his devotees, his disciples, have achieved God realization. Can you explain that?

Prabhupāda: Yes. But don't try to take advantage of it. (laughter) Don't try to give trouble to your spiritual master like that. Finish your business in this life. That is especially meant for those who are slack. His devotee, his disciple should be serious in serving spiritual master. If he is intelligent he should know that "Why should I act in such a way that my spiritual master has to take the trouble to reclaim me again? Let my business be finished in this life." That should be the right way of thinking. Not that, "Oh I am sure my spiritual master will come, let me do all nonsense." No. 

So if you have got any, I mean to say, affection for the spiritual master, then you should finish your business in this life so that he may not come again to reclaim you. Is that all right? Don't take advantage of this business. Rather, be serious to finish your business. That is a fact.

[Bhāgavad-gītā Lecture: 6.46-47 - LA, 21 Feb 1969]