The ideal of the Gaudiya Vaisnavas is to attain lila-seva in the circle of Sri Krsna’s Vrindvana lila. Thus they engage in an appropriate sadhana, one that aims at attaining a spiritual form in which to serve Sri Krsna in divine love, a gopa or gopi form. This sadhana thus involves pursuing an ideal that members of that lila exemplify. It is termed “raganuga sadhana,” which literally means “following those who have raga for Krsna.” Those who have raga for Sri Krsna are his gopas and gopis, who are eternally liberated entities. They are called “ragatmikas,” “those in whom raga is inborn.” So again, raganuga sadhana means to follow in the footsteps of the ragatmikas.
Just as those who attain the ideal of ragatmika bhakti never loose sight of it, similarly and necessarily, those whom they follow to attain this status also never loose sight of it. Indeed, the following by which one attains the ideal is something that also eternal. So to follow eternally, one needs someone to follow who is always there, not someone who is unreliable.
When Sri Krsna says that those who attain my abode never return to the material world, he is saying that this abode is of an eternally perfect nature. He says it twice, once in comparison to the worlds of the demigods. From there everyone falls. By contrast, from his abode no one falls. This is what he says in the 8th chapter of the Gita. The second time he says that those who attain my abode never return, he is pointing out the luminous nature of his abode. Here luminosity—sun, moon, fire—is used to imply that his abode is devoid of darkness/ignorance. In other words, because of its luminous nature one going there never experiences darkness. This is what he says in the 15th chapter.
So in each instance that Krsna says this in the Gita, he is not qualifying the nature of his abode to say that only those who attain it through sadhana having previously been in ignorance never return to ignorance after attaining it. He is not saying that while perfected sadhakas never again experience ignorance, my eternal associates (ragatmikas) do, which of course would make no sense.
For that matter, the abode of Krsna in essence consists of the ragatmikas love for him. That love and Krsna himself are one and different. There is no meaning to love of Krsna without Krsna, and no meaning to Krsna without love of Krsna. Just as Krsna himself does is not subject to ignorance, similarly love of Krsna—prema—is not subject to corruption. If it were, Krsna himself would not be perfect. Krsna is himself and and love of himself—Radha Krsna. The two are philosophically inseparable. Krsna is not subject to ignorance and neither is love of Krsna.
In other words, those who follow those who are never subject to ignorance, upon attaining their association, are never subject to ignorance. That is what the Gita says. Again, Krsna is not alone. Attaining him means attaining the association of his eternal associates. That is what love of Krsna involves.