It is said that after Kamadeva was burnt to ashes, Ratidevi was devasted and took to penance. Kamadeva is restored in Ananga form. The land where he is restored is known as Kamarupa (as per the Gopatha Brahmana) (could not find any text of the Gopatha Brahmana)
As per many of the Puranas, including the Kalika Purana which says:-
शम्भुनेत्राग्निनिर्दग्धः कामः शम्भोरनुग्रहात्। तत्र रूपं यतः प्राप कामरूपं ततोऽभवत्)
Kamadeva is restored by Lord Shiva. Here it is said the Rati does penance to please Shiva to restore Kamadeva.
However the Lalitopakhyana of the Brahmavaivarta Purana mentions goddess Tripura Sundari restoring Kamadeva after slaying Bhandasura. Here it is said that Rati asks Tripurasundari to restore Kamadeva.
In effect who actually restores Kamadeva in his Ananga form?