You could do one of two things:
1) You can buy a booster fan from most home centers that that you put into the existing ductwork, and that will increase the velocity going into your living room. This will require some electrical expertise on your part though, because you have to be able to tie into your furnace controls, so that the fan only runs when the furnace is running.\
2) the other way is to cut a hole in the floor in you living room for a "register boot". Then run some ductwork towards the direction of the boot, hook the boot onto the end of the duckwork, and slip the boot into the newly cut hole, and attach it to the subfloor. Then put a new register in the boot opening and you have a new floor vent.
1) You can buy a booster fan from most home centers that that you put into the existing ductwork, and that will increase the velocity going into your living room. This will require some electrical expertise on your part though, because you have to be able to tie into your furnace controls, so that the fan only runs when the furnace is running.\
2) the other way is to cut a hole in the floor in you living room for a "register boot". Then run some ductwork towards the direction of the boot, hook the boot onto the end of the duckwork, and slip the boot into the newly cut hole, and attach it to the subfloor. Then put a new register in the boot opening and you have a new floor vent.