Often, once a coil is dead, it can be revived for a few days extra use by cleaning it. Everyone has their own method, some use ETOH, some use water (I soak mine for 12 hours starting with very hot water, then rinse, and revive. The performance is fine, they just won't last as long as new coils, but it's a cost savings for sure. It really depends on the coil how well cleaning it will work, though.
Degunking coils in between flavors is a good way to increase coil life too, I don't do it that much, mainly because I run similar flavor profiles in my various tanks and know what will go with what, pretty much, and it just seems like less work. There are some flavors you just can't mix though and if you try it, you may find some of those mixes (I don't worry too much about that, pouring out a tank of juice is hardly a huge sacrifice. It can be a great way to come up with new flavors, though, too.
Best of luck,
Anna
Anna