How can I remain steadfast in repentance after returning to watching forbidden things, and are the recordings on pornographic websites that I was unable to delete considered ongoing sins, and how do I stop them, and what is the way to restore the sweetness of faith?

Preserving the obligatory duties, especially prayer, remembering the harms of sins, choosing righteous companionship and abandoning bad company, persistent supplication for a firm heart, constantly remembering Allah and striving in supererogatory acts, listening to admonitions, reading beneficial books, contemplating Allah's names and attributes, reflecting on death and what comes after it, and being mindful of Allah's awareness of His servant. And whoever repents with sincere repentance will not be harmed by the lingering effect of their sin if they are unable to remove it.