The spray is worth trying. But to up the power of the spray, use Holy Water. If you are Catholic, or know someone who is, Holy Water is easy to come by. We go through a lot at my house. My daughter gets blessed every night and every morning. I have a friend whose teenage daughter uses it every night so she won't worry about school. You can put the Holy Water into a spray bottle that that held something fragrant, such as a room sachet, and it will have a bit of a fragrance to it. Holy Water also works well on bad attitudes and poltergeists. I'm serious. Mostly because if you believe it will work, then it will. My daughter also has a dream catcher and we pray for God's protection every night. It really helped her when she started getting worried.
Also, I told her I paid to much for our house to have monsters or werewolves in it. Also, we are the first owners, so I know there is no residual energy here. Pets are good deterrents, too. We don't worry about mummies or aliens because we have cats. The dog keeps everything else away. So, if you have pets, you can tell her in all seriousness that they will protect her.
Then she can tell that weird kid that "No, you are not under my bed because my cat/dog/gerbil/bird would alert me if you were there, protect me and chase you out." and she gets to own the solution, too.
Also, make sure she gets to bed at a good hour so she won't be prone to night terrors.
Hope this helps