Reconnect to WLAN automatically

Android sometimes has this strange habit of not automatically reconnecting, when it looses connection to the router. I have an Android tablet running 24/7 using a bot to do stuff on the Internet. But sometimes, the connection breaks, and i have to manually click on the wlan symbol in the dropdown thingy the force android to reconnect the the router. This is annoying, because I have to check multple times a day, whether the bot is still working and reconnect if not. This happens approximatly once/twice a week. I'm using a Samsung Galaxy Tab SM-T230, Android 4.4.2 Does anyone know how to fix the problem/why android does that?