Keep repenting to Allah and be sincere in your repentance, and He will forgive you every time you sincerely repent. Ask Allah to help you abstain from that sin.

Narrated Abu Huraira رضي الله عنه‎ : I heard the Prophet (ﷺ) saying,

“If somebody commits a sin and then says, ‘O my Lord! I have sinned, please forgive me!’ and his Lord says, 'My slave has known that he has a Lord who forgives sins and punishes for it, I therefore have forgiven my slave (his sins).’ Then he remains without committing any sin for a while and then again commits another sin and says, 'O my Lord, I have committed another sin, please forgive me,’ and Allah says, 'My slave has known that he has a Lord who forgives sins and punishes for it, I therefore have forgiven my slave (his sin). Then he remains without Committing any another sin for a while and then commits another sin (for the third time) and says, 'O my Lord, I have committed another sin, please forgive me,’ and Allah says, 'My slave has known that he has a Lord Who forgives sins and punishes for it I therefore have forgiven My slave (his sin), he can do whatever he likes.”

[Sahih Bukhari: Book 97, Hadith 132]