It is definitely worth having a day of drinking plenty water during daytime, to give the bladder a stretch and make it less over-sensitive.
The Enuresis Nurse at the clinic where I took my daughter who had problems getting dry at night said to try this and I have tried it myself, and friends too! It definitely helps, but if you are waking a lot in the night anyway, you will be making more urine as the hormone which concentrates it overnight is not active if you are not asleep.
In general, drink plenty clear/light coloured fluids throughout the day, and keep tea and coffee to a minimum.