Allah's Messenger(saws) said: O people repent to Allah, for I verily repent to Him one hundred times a day.(Muslim 4/2076)
Our Prophet(saws) said: Whoever says:Astaghfirullahal-Adheemal-lathee laa ilaaha illaa Huwal-Hayyul-Qayyoomu wa atoobu ilayhi.(I seek the forgiveness of Allah the Mighty, Whom there is none worthy of worship except Him, the Living, the Eternal and I repent to Him.)
Allah will forgive him even if he has deserted the army's ranks.
(Abu Dawud 2/85, AtiTirmithi 5/569)