Make sure your laptop is on a hard flat surface to allow for proper airflow and to avoid overheating issues. Another reason may be the fan on your device accumulating dust and debris over time, which causes the fan to not function properly. Use compressed air in small bursts about two inches away from the fan vents to clean them.
If you have any further questions, here is a link to the troubleshooting guide for your device: [[HP TouchSmart 15-r015dx Troubleshooting#Section_TouchSmart_15_overheating]]