You cannot if it is not waived by fare rules and is applicable. Most you can do is to
1) have more than 24 hour layovers when the next available scheduled flight is not available 'today' (when you book or change)

2) get some extra stopover time in case of irregular operations (cancellations, delays etc), again normally not further then the next available scheduled flight (with destinations as per your affected ticket coupon or most likely the final destination at all).

And you can come accross some not very wise airline staff, but they will certainly be penalised for this, so you probably need to think of being a bit ethical.