The play is to continue doing exactly what you're doing, until you're able to achieve some significant capability.

In the eyes of the Iranian regime, what they're doing probably seems to be succeeding, so why change?

I really don't believe that the idea of "sanctions" is going to serve as a significant deterrent, especially since by the time sanctions get through the UN, they'll be so watered down that they'll be essentially meaningless.

If the Iranians keep doing what they're doing, they'll be able to strengthen their international alliances with folks like China and Venezuela, and those are some pretty powerful allies. Continue to make China increasingly dependent on your oil, and continue building influence and relationships with Chavez and people like him, and the end result will be a powerful coalition of anti-US sentiment.

And ultimately, weakening the US weakens Israel too (unless the Israelis get a lot smarter than they've been recently).

Keep in mind, that the Persians invented chess.