What number_6 said. I've had to recheck baggage in SIN in such situations (long layover) even when it was slightly below 24hrs due to the final destination being +2 days than original departure.
Simply, it might be even if they'd be willing to check it through in DPS it might not be possible.
However, there is a reasonably cheap "left luggage" counter landside in SIN, where you can just leave your luggage before hopping into the MRT for downtown (I assume that's part of the plan, to travel light while in SIN, and not needing cabs to schlepp heavy luggage across)