This isn't correct, as far as I recall. I think that Baby K was initially charged as a murder with attempted murder in the alternative - which isn't something I even realised was a thing - but they eventually dropped the murder element to it. It wasn't the judge ordering it, I don't think.
The fact remains that LL was only tried on the attempted murder charge in the first trial, on which the jury could not reach a verdict. She was never tried for killing Baby K and is not being tried for killing Baby K now. The trial is one of attempted murder which, by definition, is an act of failing to kill someone. Yes, the baby eventually died but LL is not being tried for her death.
Thus far, we haven't seen any evidence which is different to what was offered in the original trial, as far as I can see. Then again, it's only just started so we shall have to see what comes up over the next month or so. I'm still asking myself what the reasons were for bringing this case to a retrial rather than the others that the jury were hung on. It's all rather weird, tbh.