There, O delighter of the Kuru dynasty, he imbibes the yoga-oriented intelligence begotten in the previous embodiment, and strives again for perfection from where he had left his pursuit.
At the commencement of the Karma-yoga pursuit, Krishna had specified the unique benefits of yogic pursuit (2.40). He said, it is free from the twin defects, namely, loss of effort (abhikrama-nāśa) and adverse result (pratyavāya). That links well with what Krishna describes here.
As yogic pursuit is free from any kind of loss of effort, whatever he had done earlier remains intact, and he imbibes sufficient attention and alacrity in the new birth.
As if awakened by a dream, he picks up the thread of the previous practice and feels strongly about pursuing it with vigour and resolve. Earlier, distractions took over his mind. But now here, nothing like that will haunt him. He can and will, with intensity, take up the practice and pursue it with devotional resignation.
Gaining perfection will be fast and a matter of ease, comfort and certainty.