To repair such a setting in LT2008 or higher, redefine the block(s) with the SETBYLAYER command.
In older AutoCAD versions you can use the BEDIT or BLOCK commands to redefine the block(s), choice is limited by your LT version. ◦
Tips and Tricks to get the maximum out of the most minimum of AutoCAD versions.
Redefine block entities to ByLayer