Upping the cure time won't really make a difference, as bulb placement is important, if one is out then the fingers under that bulb will not cure properly.
How many hours do you have left on your lamp it is unusual for a bulb to go before the 100 hours.
I would remove and replace the bulbs as it may just be a connection playing up. I have a bulb in one of my CND Lamps needs a little wiggle every so often as it can sometimes not go on.
Also make sure in future you always have spare bulbs I always order them when I replace bulbs, even though I now have 3 lamps!