Why didnt Data create Lal v2.0?

[newtontomato539]

He could have saved her memories and her emotions. Bring her back!

 

[Captain McBain]

I never understood why Data couldn't succeed at making an android. In "A Measure of a Man," there's a certain problem in building a positronic net that Data relays to Commander Maddox while in the observation lounge. My question is why Data didn't copy his own design exactly---as a working android, his design obviously allows for a functioning android---so why not use this precise blueprint for Lal?

That's exactly what he did,

If that's 'exactly what he did,' then why didn't Lal function, as Data obviously was able to?