As I was playing "StarCraft 2: Heart of the Swarm" my internet went offline at a certain point and I missed the "Fashion Statement" achievement. I did what was necessary to gain it but since I was offline it was not registered. The requirements are:
Show off your new look to the following characters [Izsha, Abathur, Zurvan].
Since I moved on and finished the campaign I wonder: can I somehow go back and gain the achievement without starting a new campaign?
If you have a save file from the campaign, you could load that and complete your achievement. Note that the autosave in 3.0 only stores up to 25 save files, so if you've started Legacy of the Void, chances are you've lost your autosaves from Heart of the Swarm.
Otherwise, I think you'll have to start a new campaign. The master archives lets you re-earn mission achievements, but they don't let you return to the Leviathan. Thus, you are unable to get achievements that happen between missions like talking to characters (Fashion Statement, Rally the Troops, etc.) or clicking on objects (Star Tours) without starting a new campaign.
