Listing ranking falling

Hi everyone, over the last year my sales have dropped about 50% even with a 30% price decrease. There are a few more competitors but it doesn’t seem to be much more competitive. Slowly my ranking has dropped and key words that I used to be 1st for, I am now ranked 10-20. My product is a restricted product so I can not advertise and I need to be careful about which key word I use so I don’t get flagged and have my listing taken down. I plan on trying to optimize my listing but are there other ways such as decreasing price for a few months to increase sales and ranking and then increasing price again? It seems like loss of traffic is the main reason for this decrease in sales. Thanks in advance!