The Raspberry Pi has holes for mounting a reset header (marked RUN on the Raspberry Pi 3/2 and P6 on the Raspberry Pi 1 Model A and Model B Rev 2). The reset pin allows the device to be reset using a button rather than removing the micro USB connector each time to cycle the power:
To make use of it, you will need to solder a wire or pin header to the Raspberry Pi and connect a button to it (or briefly touch a wire between the two holes each time). Alternatively, we can extend our previous circuit, as ...