I have a year old ear cartilage piercing that hasn't healed--it gets red and puffy on & off. I use saline washes & warm compresses. What should I do?

Ear pierce/infection. If this is a chronic subacute infection than the cartilage is your issue. It is serving as a nitus for recurrent cellulitis/infection. Best to see ENT?Plastic Surgeon to incise, open , remove damaged tissue including the cartilage. Than allow healing by secondary intention or suture closure. Make sure on PO antibiotics and maybe even obtain a C&S of the tissue to see if strange organism is growing.
Take earring out. I assume you are continuing to use the earring. Chronic infection. Take earring out. Will probably heal and seal opening. You can then redo piercing. If ring already out, see ENT surgeon for management.