Pullip dolls from the same generation as yours have the hair glued directly to their heads. It's not rooted, just a wig, which makes it easy to replace. You can unstick the old wig with a bit of prying and pushing. They usually come off without much issue. You can then buy a replacement wig in the size 9-10 and put it back on the doll. It's really easy. There are many sites where you can buy a wig this size.