1) apparently if you swap the nuts over L to R and the R to L the cleat bit (where the nut was staked )comes in a different place  allowing second use of the nut.
 
2) I've seen the nuts reused on the same side but with a smear of THREAD LOCKING  compound applied, then the nut restaked.
3)buy  new nuts
your choice 1 or 2 or 3
                
 wirecutterman
                
 January 2010