Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
Taking loans with usury is forbidden. The one who gets involved in that sin should ask forgiveness of Allah and make sincere repentance towards Allah. And if one can return the initial amount without adding interest to it, he has to do so; otherwise, he should pay interest as soon as possible, to be free himself from such Haram dealings.
If one repents from his sin of purchasing a house through usury then he may sell his house with a higher price, and may use its rent if he rents it out.
As for expiation for the above sin it is making sincere repentance, asking forgiveness of Allah, and increasing good deeds. Allah Says (interpretation of meaning): {….Verily, the good deeds remove the evil deeds (i.e. small sins)….}[11:114].
Allah knows best.