How can one get rid of the habit of masturbation, which causes sadness and leads to missing prayers, and is repentance from it possible despite repeatedly returning to it?

Repentance from sin is not difficult to attain for whoever seeks Allah’s help and genuinely turns to Him. Allah Almighty says: "And those who strive for Us – We will surely guide them to Our ways. And indeed, Allah is with the doers of good." (Al-Ankabut: 69). Continue to repeat repentance whenever you sin until Allah bestows upon you sincere repentance. What helps with this is reflecting on the gravity of sin, reflecting on Allah’s Names and Attributes, and reflecting on death and what comes after it. Also helpful are adhering to remembrance (dhikr) and supplication (du'a), guarding against evil thoughts and replacing them with what is beneficial, staying away from everything that incites lust, frequently fasting, and keeping company with the righteous.