Yes female dragons can still lay infertile eggs. Try lifting her up by her front legs carefully and look at her belly, often times you can see the bumps from eggs. If your girl is getting ready to lay eggs, get yourself a large (18+ gallon) bin and fill with equal parts organic potting soil (no pesticides or fertilizers) and play sand (from the hardware store, no pet store sand). Mix it up and moisten it until it's diggable (you can easily dig tunnels that don't collapse). Be careful not to put too much water. Put your female and here and observe her, if she starts to dig like crazy she probably had eggs. Put her in the laying bin once a day for about an hour (again just a rough estimate), and see if she lays eggs. If she does it is best to freeze the eggs for about 24 hours in the freezer (in the off chance they any of them somehow did get fertilized) and then toss them in the trash or compost them.
Also, it's not a bad idea to double check your husbandry to look for other causes of this change in behavior (improper temps or UVB for example).
Let us know if you have any questions about anything mentioned above or on the caresheet!
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