If you get rid of the nest and match them up to males to lay eggs too quickly it could actually be a health risk for your girls. I would suggest removing the infertile eggs and replacing them with dummy eggs. Let them grow bored of their eggs this time or remove them after the correct amount of "sitting" time. Then remove the nest completely and let their bodies build back up nutrients before even considering breeding them for real. Cockatiels have a tendency to become "chronic" egg layers. This can cause health risks such as vitamin deficiencies and even egg binding. After a good period of "rest" time you could them match them up to males if that is what you are wanting. Although if possible it might even be best to let them sit out one season to build back up their health and then match them up with mates.