Train conversion to express - the travel time will be the same and double the fare will find no takers
SL and 3AC coaches - may have decent patronage in up direction, will run 90% vacant in down direction
Extension to Deoghar - does not make sense to extend a train for 10 km journey. There are plenty of travel options. Extending this train to Dumka (with TT revision and express timings) will make sense.