Is a sincere repentance after which one does not return better, or a repeated repentance with a return to the same sin?

The best is sincere repentance and steadfastness. However, if one stumbles and returns to sin, one should not despair of Allah's mercy. Rather, repentance must be renewed no matter how many times the sin is repeated, for Allah accepts the repentance of His servants, pardons evil deeds, and forgives all sins, and "the one who repents from sin is like one who has no sin."