What can be done in the very short term is restoring western missile bases and unlocking the missiles and launchers inside it, spreading them to safe locations to avoid being blocked again
It should not take more than a week to do it (it's probably already done by now as it should be the top 1 priority)
Iran on the short term cannot secure the airspace besides bringing up the SAMs that were not active, but it can restore its firepower
Iran's missiles are fine, we still have a lot of launchers with some having been destroyed but so far no proof for the "400 launcher destroyed", we had not more than 10 IDF videos of launchers destroyed, and some of them were decoys with no secondary explosion
Another smart move Iran can do is to move K/K-4 and its launchers close to Pakistan/Afghanistan and fire them safely from there to Israel (they have 3000-4000km range so it's largely enough). Israel will have a hard time reaching to Pakistan border