You can save the game, quit and reload with 'No Maintenance' checked to pause all ships' clocks, but they will continue to break down at their current rate. You can SM in nigh-infinite Maintenance Supplies to all your ships to keep them repairing themselves until you can overhaul them. You can replace as many of your ships as you want with 'Fast OOB' new ships of the same class(es) (thus Maint Clocks of 0.0) and SM move them to the appropriate Fleets & Locations, transfer all crew, officers, and cargo to the new ship and remove the old ones.
But unless you saved your game database in an earlier state, no, there is no way to go backwards in Aurora time to undo an action.