Your reaction is probably complete.
do be careful dropping water down the condenser with the reaction running. You can have so much PI3 form that the water dissolves most of it but not all of it and if the reaction is still hot, you build pressure underneath and blow the PI3 plug and the HI formed out of the condenser. I do not recommend this, for obvious reasons.
why do you assume you have to have bubbling for all forty eight hours? As long as the contents of the flask are moving around by convection currents you have enough movement for the reaction to complete. If you a have a complete cessation of bubbling after forty hours, you are most likely completely reduced anyway.
