What's the Point of Negotiating a "New" Nuclear Treaty With Iran When It Did What It Could to Circumvent the Last One?

Last time around the Grandiose Ayatollah's minions pulled a fast one by, for example,

concealing titanium tubes inside steel pipes to using its petrochemical industry as a cover to obtain items for a heavy-water nuclear reactor.

Kind of reminds me of that little old oil-for-food scheme the UN once pimped for. As I recall, that one turned out really well, too, didn't it?