You have to get all the 3000 diamond off the stone and out of the crevices that form in the glue that the stones glued to the dop with.
I hold the dop vertically with a tissue round it and wash the stone with an artists size brush with that alcohol based liquid you get at the hardware. Have a small stiff brush to clean out the crevices.
After charging the lap with 3000 grit, just use the outer half of the lap. Initially the stone will pick up a lot of diamond/oil mix, but after a short period the lap surface will become much drier. That’s the sort of surface you want, as it dries further occasionally move the stone into the wet area to pick up more diamond.
The lap speed I use for 3000 grit on a Batt lap is about 300rpm.