Given the situation, the best thing to do is to take the necessary steps to break your budgie's egg laying cycle and this is done by removing the recently laid egg and by not giving your budgie anything that she can use as a nest.
It will be helpful to totally rearrange her cage or even better, to place her on a different cage if you have a spare one.
By doing this, the change will promote the break on her egg laying cycle and this will also encourage your budgie to come out of breeding condition.
For detailed information, you can check this link: https://talkbudgies.com/budgie-breedi...want-eggs.html
How old is your Mimic?
Does she have a steady source of calcium and minerals (through cuttlefish bone/calcium block and mineral block)?
If your Mimic is taking a lot of time to recover from laying this first egg, then she has likely strained a whole lot and for her overall welfare, it's best to really keep a close eye on her and if she continues to not feel well, then having her examined by an avian vet specialist would be the best thing to do.
Her calcium levels may be dangerously low and the vet may have to address this promptly.
I'm wishing your Mimic a steady recovery and hope she will not lay more eggs.
Best of luck!