To increase the distance your servo can move you will need to adjust the upper and lower limits in your code.
When you create a new servo object in node js there are two parameters for low limit and high limit which are preset to 1.0ms and 2.0ms.
servo = new Servo(0x40, 1.0, 2.0, true);
Try reducing the 1.0 value in 0.1 increments until you reach the lower limit of your servo and then increase the 2.0 value in 0.1 increments to get the upper limit of your servo.
You can also set the limits for individual channels using the setLowLimit(low_limit, channel) and setHighLimit(high_limit, channel) functions.
The readme file on our github page for the Servo Pi node js library contains more details on how each of the functions can be used, you can find it at https://github.com/abelectronicsuk/ABElectronics_NodeJS_Libraries/tree/master/lib/servopi