Repeatedly using a launcher can wear out the mechanism present inside it. But you will have to use the launcher a lot either to practice new skills or to play matches. But when you are not doing any of the above then try not to simply pull the ripcord or string of your launcher just for fun. Over time it will dull the gears inside the launcher.
If you are thinking of using water and such to clean the launcher then don't do it. You can clean the outer shell using a damp cloth and some cleaning component but don't dunk the whole launcher in water. This will either end up loosening the gears or tightening it too much which will later on make it difficult to use the launcher and fire up the Beyblade.