Unfortunately you can't do much. iOs 9 will help solve this, if other users are experiencing this apple might create a fix but for now just be patient and wait.
Across the entire operating system, apps and key technologies have been made more efficient to trim battery usage wherever possible — so you get more battery life for the things you do every day. Thanks to ambient light and proximity sensors, your iPhone knows if it’s facedown on the table and prevents the screen from turning on, even when you receive a notification. And the new Low Power mode lets you extend your battery life even further.
1hour
OF ADDITIONAL TIME BEFORE CHARGING