If I repent at noon, but half an hour after the time for Dhuhr prayer, must I perform the Dhuhr prayer immediately after repenting, or should I wait for the Asr prayer to start praying anew?

It is not permissible for a worshiper to delay the Dhuhr prayer beyond its prescribed time or to combine it with the Asr prayer without a legitimate excuse, such as travel or illness. Whoever becomes obligated to pray before the time for it expires, such as one who reaches puberty, recovers from a fainting spell, or a woman who becomes pure from menstruation, prayer becomes obligatory upon them if they catch a period of time sufficient for the takbirat al-ihram, or for one rak'ah according to the more preponderant opinion, based on the Prophet's saying: "Whoever catches one rak'ah of the prayer has caught the prayer." Regarding one who abandons prayer out of negligence and laziness, there is a difference of opinion concerning their ruling. Those who rule that such a person is a disbeliever do not require them to make up the prayers after repentance. Those who do not rule that they are a disbeliever obligate them to make up all missed prayers.