Position control in closed loop relative mode in infinite range

Hi All,
 I need to make a position control of a DC motor. For this purpose I found that closed loop relative mode is the best for me.
However the !G command can have values between -1000 and 1000. How can you extend the motion range of the DC motor? If I increase the encoder min and max values, the range extends, but the resolution of the command becomes worse.
The application is a robot that runs on the floor, so the motion range cannot be determined in advance.
Controller type: SBL2360t
Any help is highly appreciated.
Balázs