Does a servant's committing a sin again after repenting from it invalidate their previous repentance and prevent them from being forgiven for the sins they repented from?

If a servant repents with sincere repentance that fulfills its conditions, and then returns to the same sin, his previous repentance is not invalidated. He is treated as one who committed the sin for the first time, and he must repent of the sin to which he returned. The validity of repentance depends on abandoning the sin, regretting it, and having a firm resolve to forsake it, not on never returning to it again.