Is it possible to repurpose this sound bar to use as speakers at the back of the room instead I'm purchasing a better speaker and woofer for the front.
If you have an av receiver and it has just a standard speaker cable input maybe... but as most don't have that input now I'd probably say not. The soundbars are too smart for them to be repurposed as a dumb rear speaker.
If its a new soundbar you have these might be an option they are wireless (kind of power cable and cable to each other) and they link to the newer soundbars.