I had to look up "DTG" to see what you were talking about.
Depending on the stepper that is in the printer you are modifying, you most likely be able to find one with greater torque and the same deg/step rating. Most common is 1.8 deg/step giving you 200 steps/revolution. If you do go to a higher power motor, you may need to add an additional power circuit to drive it from the printer.
You could put a limit switch on the moving table that would be hit when the print is done that would latch a relay (holding circuit) that would reverse the leads to the stepper putting it in reverse. Then a second limit at the home position could energize a relay to stop the movement by disconnecting the motor reversed connections on the holding relay. A time delay relay could reset the holding relay to start again. This way a "page feed" after printing would reset the table.