If it was alive when you started the eggtopsy I would keep them in. If it was dead, I would candle and look for life, eggtopsy non-movers.
My incubators normally have stable temps and hatching day is quite predictable for me. If mine aren't out on the evening of day 21, they aren't going to come out. If you have had unstable temps or are not 100% sure the thermometer is accurate, keep them in 2 days over.