I wouldn't use superglue that seems a bit extreme, I always used pva with the smallest amount of water, best way to open up a small crack it to get a wood wedge and sharpen it right up and tap into the crack. or you could dowel through one side to the other ( have seen some companies do this for toe support go through the splice and out the other side glue the dowel rod and tap it through cut off and sand it to blend in, will have to be a really nice fit to benefit though... but not too snug ;-)