You mean the part that follows AFTER the leper is healed? You might want to reread that
Cleansing From Defiling Skin Diseases
14 The Lord said to Moses, 2 “These are the regulations for any diseased person at the time of their ceremonial cleansing, when they are brought to the priest: 3 The priest is to go outside the camp and examine them. If they have been healed of their defiling skin disease,[a] 4 the priest shall order that two live clean birds and some cedar wood, scarlet yarn and hyssop be brought for the person to be cleansed. 5 Then the priest shall order that one of the birds be killed over fresh water in a clay pot. 6 He is then to take the live bird and dip it, together with the cedar wood, the scarlet yarn and the hyssop, into the blood of the bird that was killed over the fresh water. 7 Seven times he shall sprinkle the one to be cleansed of the defiling disease, and then pronounce them clean. After that, he is to release the live bird in the open fields.
I mean that the bird blood recipe given doesn't cure leprosy