Sol's plan was to stall for time to kill Vito and to make a deal:

His original strategy after being turned down was to whack Vito, which would remove an immovable object from his path. A good deal of Vito's police/political protection would bolt rather than stand with Sonny the hothead, putting them up for grabs for Sol, Tatt and Barzini. Then Sol could use Sonny's greatly weakened position to bargain for the Corleones' remaining protection at a reduced rate.

Vito's survival didn't change the strategy. As long as he lived, there'd be no deal, and Sonny would be gunning for him. So, yes, he was stalling for another shot at Vito. And, yes, if he succeeded, he'd then present Sonny with a (greatly reduced) deal, hoping that Tom would make him see that he had no choice but to accept.