What is the ruling on one who commits to several months then returns to sin, and fears returning to it despite repeated repentance?

To escape the devil's snare, rely on Allah and seek His help. Satan is an enemy who seeks to corrupt a person's religion and turn him away from repentance. Therefore, you must seek forgiveness and offer sincere repentance whenever you fall into sin, for "the one who repents from sin is like one who has no sin." Part of your repentance is also to abandon the forbidden act of masturbation, for its perpetrator is considered among the transgressors.