I like to top back up if I feel I got a good feel for the players on the table. If Im at an early stage I like to wait a little. Lets say I sit down and loose 20 x the first thing I do. In that case I like to hang around a little bit more to get a chance to get some reads before I rebuy. Right?
But I think that you should rebuy as soon as you loose a couple bucks if you like the table.