You know, as any other languages , Farsi has formal and informal words. That's why you hear many versions with different words! We say:
هفته ی آینده میبینمت (hafteye ayande mibinamet)
هفته ی آینده میبینمتون (hafteye ayande mibinametoon)''more formal''
هفته ی بعد میبینمت (hafteye ba'd mibinamet)
هفته ی بعد میبینمتون (hafteye ba'd mibinametoon) ''formal''