If Aer Lingus did want to add an extra A320, there's probably the business for it now. They'd have Warsaw and Budapest to themselves. Amsterdam, Paris and Manchester could probably take more rotations as well. There were 138 pax on the Amsterdam-Cork service last night and if you're achieving an 80% load on a Thursday evening in January, there should be few worries about making it double daily every day in the summer too. Perhaps with Ryanair gone from the route out of Shannon, Madrid may become an option again.
In the meantime, all other avenues should be pursued to get a renewed service to Warsaw. Other than CentralWings, who has aircraft based in Warsaw? LOT, Wizzair and Norwegian spring to mind. Any others?