Purport

Bhagvan Shri Krishna described that a genuine human who has pure devotion towards God and good intentions righteousness is saved even they fail in the present life. Describing two situations, Bhagvan explained that those who fail early are born into the family of pious and well-established people. Others who fail at some higher state of spirituality take birth in the family of a great yogi.

In this Shloka, Bhagvan Shri Krishna declares that such a person starts from where they have left in earlier life. He is also fulfilled with what he lacked in earlier life. With his deficiencies removed, he further moves the path of enlightenment without many difficulties. 

So, once a human devoted himself to Bhagvan Shri Krishna with pure intention, he never falls. He only moves higher and higher in the journey of enlightenment. He finally achieves the liberation in from iteration of rebirths. Somebody who tries more attains liberation early; others who are weak in his attempt may take some more time. But in either case, a true devotee and genuine yogi is always liberated.