Hardware offline after hours of operation

Hi guys
I am using blynk app to monitor temperature using ds18b20 sensor connected to arduino mega with esp-07 as a wifi adapter. Every thing works fine and I can enter blynk app from work to see temperature in my home. My problem appears after several hours of operation (around 10 hours) when the hardware appear to be offline and cannot be accessed, and it does not respond untill I reset the board again. Is it a common issue? If not, how can I modify my code in order to check connection and auto-reset my board when it is lost?