Actually, you can. As @amberose mentioned it’s not about the number of your reads, reader retention is a rate of how many people finished reading your story. If you have only 20 readers, but all of them finished your story, then your reader retention is 100%.
Also, Episode is always looking for hidden gems, so if you write a really good story, you have the chance to get featured sometime regardless the number of your reads. And the same goes for being visible in the trending: it doesn’t matter how many reads your story has overall, your rank will be determined by the number of people reading it at the same time. So yeah, keep updating 