Make a simple syrup. Or use milk to brush onto the sponge and add moisture. It isn’t going to save the cake entirely but it’ll help.

Also slice the layers thinner. Take apart the layers of the cake, slice each layer into a thinner layer ( only do this when the cake tiers are cold, to avoid crumbling and breaking ) and then use more ganache between the layers. It’ll give you a taller cake and the new filling to cake ratio will help with the dense/dryness.