Have you considered cleaning and staining what you have, old pressure
treated if not rotted and deck was well made is worth the effort as rot
is your #1 concern. Cracking of wood is normal and new will crack also.
An old deck can look like new. Also new pressure treated here is not CCA
it is a new formulation that needs stainless fasteners and rot
effectivness has not been proven yet. For the effort and cost consider a
deck cleaner, powerwash and transparent stain. My pressure treated is
20 yrs old when I redo it every few years it looks like new. I hope to
never replace it, to costly.