with LRs definitely is tricky. Roly's and Dons suggestions are great especially when your purpose is to do a flavor switch from a "bad" one to one you prefer. As for the suggestion to bin them when the atty isn't performing any more is for the most part right, there really isn't a guaranteed way to prolong the life of an atty, But I would say prior to ditching them do I final desperate effort to squeeze a few more vapes out of it.
Try "Dry Burning", though doesn't necessarily work all the time, works well if your atty's performance is effected by being gunked up with think
juice build up.
I have salvaged a few (not all ) LR's by doing this method, but I only try this when the atty really doesn't produce much vape at all (next to none) no matter how hard I try.
check out this vid made by one of our seasoned vaporers Dumalta
Worse case you end up ditching it anyway.
LGD