After their 2012 Nutcracker revamp, Boston Ballet artistic director  Mikko Nissinen and designer Robert Perdziola set their sights on another classic, teaming up again to retool Swan Lake for this past season’s opening night smash. Fresh sets, costumes and choreography brought new life to the ballet, including a stunning scene in which 24 swan maidens emerged from a thick fog. The production proved so popular that some would-be attendees had to be turned away even after the run was extended. But take heart, balletomanes: The show will be back in April.