Do you only have the one hen? They will usually lay until they get as many as they want to sit on, and will eventually spend more and more time on the nest, then they will stop laying, and commence to sitting more consistently.
Depending on how many you have laying, and how many you want to let her sit on, I'd mark them (sharpie marker), candle them, and remove any that are older than about 10-14 days old. Keep the freshest ones out there for her. Don't remove the same amount every day, let her build them up a bit, so you will know when she thinks she has enough. After she commits for a few days, you can remove any that have gotten too old.