After the next guildleve reset, you can exchange them for new leves.
Wrong. That is regional leves, that is to say, battle and gathering leves. Crafting leves, which are local leves, are never exchanged. A local leve should disappear from your journal as soon as you have used the last of the leve-provided materials without producing the requested number of items. If this is not the case, you should contact a GM. This is, unfortunately, not the first time I have heard of this, although I have not experienced it myself. Edited, Oct 13th 2010 11:24pm by ChrisMattern