You will most likely need to change the display assembly.
To clarify the LCD, digitiser all together. Any Sony Xperia where the glass cracks renders the touch screen unusable anyway.
So you will need to replace the whole screen, you can't just replace it separately as they are fused together and is not a diy repair to replace glass only.
Guide to replacing screen:
Sony Xperia Z Display Assembly Replacement
Where to buy the part:
eBay - http://www.ebay.com.au/itm/Black-NEW-LCD...
Eddogo - http://www.eddogo.com/original-lcd-displ...
Screen adhesive from Eddogo: http://www.eddogo.com/front-back-sticky-...