The Prophet (sallahu alayhi wa salaam) said:
“Indeed, Eemaan gets worn out within one of you just as a tattered garment is worn out. Thus, ask Allaah to renew the Eemaan in your hearts.”
It was also reported in al-Musnad and other books from Aboo Hurayrah (radiyallahu-unhu) that the Messenger of Allah ( sallahu alayhi wa salaam) said;
“ Renew Your Eemaan” It was inquired “ Messenger of Allaah, how do we renew our Eemaan?” He replied,
“Say Laa Ilaaha Illallaah often.”
This means that frequent repetition of it renews Eemaan in the heart, fills it with light, and increases it in conviction and sincerity. However, making such a state reality requires consistent action, struggling with one’s soul, and constant mindfulness, since Aqeedah is not just a text which you read at a certain stage of learning and then eventually finish; or which you read to a Shaykh in a masjid and then stop.
Rather, Aqeedah is something which must remain with you throughout life, constantly at all times.
Explaining “A comprehensive Hadeeth about ‘Aqeedah” by Shaykh ‘Abdur-Razzaaq ibn ‘Abdil-Muhsin al-Badr pg.7-8