What should I do if I unintentionally utter something that necessitates disbelief (kufr), and must I repent every time I fall into that?

Slandering Allah the Almighty, or the prophets, or the angels, and jokes that include mockery or ridicule of Allah, or His messengers, or the Quran, or the rulings of the religion, are acts of apostasy that expel one from the fold of Islam, based on the Almighty's saying: "And if you ask them, they will surely say, 'We were only indulging in idle talk and play.' Say, 'Is it in Allah and His verses and His Messenger that you were mocking?' Make no excuse; you have disbelieved after your belief." If you uttered these words knowingly and willingly, then apostasy has occurred, and you must perform sincere repentance, recite the two declarations of faith (Shahadatayn), and promptly embark on a new life in Islam, while controlling your tongue. For "Indeed, a servant may utter a word that displeases Allah, paying no attention to it, and he will fall into Hellfire because of it."