Is it necessary to make up the prayers that were combined and shortened without a valid excuse, or is repentance sufficient for them?

"Leaving prayer entirely is considered an act of disbelief (kufr) that expels one from the faith, according to some scholars. As for those who pray sometimes and miss sometimes, there is a difference of opinion among scholars regarding whether this constitutes disbelief or not. Scholars also differ on making up prayers intentionally missed. Some obligate making them up, just as a sleeping or forgetful person would make them up. Others believe that making them up is not obligatory, either because leaving prayer is disbelief, in which case the prayer is not beneficial, or because a time-bound act of worship is not accepted if performed outside its prescribed time without a valid excuse. The ruling on shortening or combining prayers while resident does not differ from abandoning them. A prayer from which a pillar is intentionally omitted becomes invalid. And whoever prays a prayer intentionally missing a unit (rak'ah), a prostration (sajdah), or a pillar is like one who has not prayed it at all, and is in grave danger. It is not permissible to combine two prayers without a legitimate religious excuse, and whoever does so is sinful for violating the texts that specify the prayer times. Whoever prays before its time, knowing and intentionally, is sinful and must repeat it. And whoever delays it beyond its time, knowing and intentionally, without an excuse, is sinful, and their prayer is not accepted, according to the preponderant view. What is obligatory is sincere repentance and making up the prayers that were shortened or combined while resident without an excuse, and performing abundant supererogatory prayers."