If you had a good burr once, but due to use it is now dull, you can refresh the edge a couple of times (depending on how hard the use it has seen) by just re burnishing the edge - - ie.  just roll a new burr without refiling or re-stoning.  You can do this a few times, usually, before it gets so bad that you have to refile and restone - - or use the belt sander, etc.  Once done, you can feel the burr with your fingernail, to see if you have enough and if it is smooth (no nicks).  
Russ