This system takes into consideration only the last 30 days, so you'd have to report at least one price per day to maintain the top spot. Once you miss a day, it takes 30 consecutive days of price reporting to make up for that missed day. Meanwhile, if another member reports steadily, not missing a day in 30 days, they will pass you in the list.
Ensure location services are enabled and you are reporting at the station for price reports to count.