I think you can improve your child's interest by reading children's books in the desired language. I like the 部首拼拼事书 for Mandarin Chinese. There are also free children's books on Storyjumper. For example, Terry, Yes You Can!
Perhaps as a parent you can find some activities for your child, for example going on holiday where the language is spoken or watching a movie in that language. For example, Over the Moon.