Rick Riordan has said he's not planning a new *Camp Half-Blood* book right now, but he is working on other projects.
If you're looking for more in the same world, you can check out:
* The Trials of Apollo series: A five-book series that follows Apollo, the Greek god of music, poetry, and light, as he's turned into a mortal and must regain his powers and save the world.
* Magnus Chase series: A three-book series that follows Magnus Chase, a homeless teenager who discovers he's a son of Frey, the Norse god of fertility.
* The Kane Chronicles series: A three-book series that follows the adventures of two siblings, Sadie and Carter, who are descendants of the ancient Egyptian gods.
* Percy Jackson and the Olympians series: The original series that started it all!
Let me know if you'd like more information about any of those series.