Sometimes text is way too long to hold your child’s interest. Or a book just doesn't grab your child.
You are the best judge of your child’s waning attention. Use your judgment. If you sense your child is
losing interest, and you think the book has enough to merit to continue reading, you
have some choices.
You can tell rather than read the tale.
You can skip some description.
You can summarize a bit.
You can let your child narrate.
See where the pages take you . . . or just put the book down and find a better book for your child!