Of course put the diaper back on...with duct tape if she tries to take it off. Obviously she has gotten tjust what she wanted, attention and now knows it works!!
I have tried to give advise onthis issue before. I tried to potty train my eldest but with four child born in five years he reverted and I changed my tactics.
I neve pooty trained a child again! they just use their bowels to control us!
take them with you to buy the underpats ( only three ), unwrape andafter showing them to the child put them on a high shelf. Now the hard part...no negotiating... they get their diaper off and get on the toliet , without any help. The call you to be wiped ( at first but hen you let them try) . They ten put the same diaper back on. When the diaper has been dry for three weeks 9 day and night0) then you let them wear the underpants for a few hours at a time. They must know that this is a privelege and not someothing YOU are taking the creidt for ( so often parents love to bag ' my child was potty trained at ___age) . Why does so much of what they do have to belong to us???
Of course they cannot go to certain preschools if in a diaper etc. and you may feel as if the other parents think you are not a good parent etc. but in the end you child will NOT be screwed up. I often meet certain adults and wonder about their potty training experience.
Some children are ready sooner than other. many are terrified of that huge white porclain thing that 'eats' thngs...like maybe them?? It looks small to us but huge to them...and often scary.those parent who let thier children watch them go tot he bathorrom can also create another problem as the men are obviously larger than the child and all of us have 'hair ' that they don't. identity crisis???
Best of luck. be firm and don't make it all about YOU