I would propose that this is an example of thematic development. Especially since your example comes from a soundtrack, it's pretty clear that this type of development is ultimately based in the development of Leitmotive that dates back to Wagner and earlier.
Thematic development, in its most broad sense, can be any variation of a theme. It can be varied harmonically, rhythmically, texturally, etc., and it can either be varied in full or can be fragmented into smaller sections that are then developed (something we call fragmentation).
I think it's important that you say the entire melody is being changed. This is why I would call this thematic development as opposed to motivic development, which typically handles smaller cells as opposed to larger melodies.