Board Thread:Q & A/@comment-14.203.35.141-20150217143216/@comment-24397663-20150217152530

Because it's not the kiss, but his blood that did it. And since Adalind was infused once with Nicks blood, it wouldn't work a second time. Same goes probably for Juliette, for she 'got' her hexenbiest from Adalind.

Like Henrietta said - there is no 'cure' for her - and she knew about Nick very well. Had his blood been a possible cure, she would've said so.