If I am unsuccessful in achieving success in Krishna conciousness in this life, what will happen in my next life?

If a person engaged in yoga, the process of self-realization, somehow or other fails to complete the process, he is given another chance; he is given birth in a family of a pure brahmana or a rich man. If one is fortunate enough to take birth in such a family, he gets all facilities to understand the importance of self-realization. From the very beginning of life our Krishna conscious children are getting the opportunity to learn how to chant and dance, so when they are grown up they will not change, but instead will automatically make progress. They are very fortunate. Regardless of whether he is born in America or Europe, a child will advance if his father and mother are devotees. He gets this opportunity. If a child takes birth in a family of devotees, this means that in his last life he had already taken to the yoga process, but somehow or other he could not finish it. Therefore the child is given another opportunity to make progress under the care of a good father and mother so that he will again advance. In this way, as soon as one completes his development of God consciousness, then he no longer has to take birth in this material world but returns to the spiritual world.

Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “The Science of Self-Realization”, Page 157