1) Check the Lenovo Vantage app. It will tell you battery condition. It also allows what is called a "threshold". If the battery reaches this threshold (i.e. 75%), the battery will stop charging and display "plugged in and not charging".
2) If that didn't pan out, turn off the laptop, unplug the charge cable, and remove the battery for a bit. Hold down the power button for 30 seconds. Then put the battery back and charge cable back in. If this still doesn't resolve it, look toward either a new battery or charger.