Is it obligatory to make up supererogatory prayers that were performed with an incomplete ablution? And how are supererogatory prayers made up for someone who was not diligent in performing them?

Voluntary prayers (Nawafil) that were performed without ablution (wudu) or after their prescribed time do not need to be made up, because they are not obligatory in the first place. Scholars have differed regarding the permissibility of making up regular voluntary prayers (Nawafil Ratibah). The Shafi'is hold that it is recommended to make them up, while the Hanafis and Malikis do not see the need to make them up. Whoever has obligatory prayers (Fara'id) to make up should start with them and not become preoccupied with voluntary prayers instead, due to the Prophet's (peace be upon him) saying in the Hadith Qudsi: "My servant does not draw near to Me with anything more beloved to Me than what I have enjoined upon him." Al-Akhdari also mentioned that whoever has missed obligatory prayers to make up should not perform voluntary ones.