It does have the functionality of needing to exceed one of your previous highest metrics of some combined statistics. At least, that is my belief because, after a certain threshold, it becomes very hard to get back to trending, if not impossible. You need to 2x your metrics, but I also found that it has some kind of fall-off date or something. Mainly because there was someone I followed who had a decent/high following but then went on a hiatus. Returning after more than a month, the first chapter released immediately put the story back to n1 on trending the following day.
Of course, this is just my observations and I know jack shit about it so take my words with a spoonful of salt and saline solution.