Remarrying one's ex-husband after khula'

Khula' is a talaaq-e-baain. After the khula' is conducted the nikaah terminates and the wife will have to sit in iddat. If both wish to reunite in the iddat or after the iddat, then it is permissible provided a new nikaah is performed with a new mahr and on condition that the husband did not issue two talaaqs prior to the khula'.

And Allah Ta'ala (الله تعالى) knows best.