I started a story and published it online in 2016. And then I disappeared due to various unavoidable priorities in life. But now I want to restart. But I am not sure. There are already less views. Plus, the write up is pretty old (almost more than 2.5 years). So first, should I even attempt? And Even If I'll attempt, how to invoke interest in reader's mind?
It can't hurt to try.
If you have an idea for a story you can do it. For example there may still be some people around that have you "bookmarked" or are "following" you or whatever the system to keep track of authors / stories you are interested in is called where you want to post it. Maybe you are lucky and they will look at your post because it appears in their "timeline" / "reading list" / ...
Continuing a story with 2.5 years absence is probably a bit difficult if you didn't have a bestselling book because you have most likely lost all the momentum you may have built up when you first worked on it. But that may lead to a bit more momentum when you start again nowadays. But I'd view it similar to when you started with the story. You need to build your readership again.
You definitely have to make sure that everyone understands what's going on. If it's in the form of a blog post you should definitely link to the older parts and you should explain in your story whatever is relevant - characters, setting, ... Similar to having a long-running series or continuing with the third book in a series of novels. Make sure your readers know what is happening and why it is happening.
If it's been a long time and you feel like the story is not quite the same anymore you could also think about "re-booting" it. Start anew with a few differences in cast, setting, conflict, ... Maybe it even fits your story to explore a different strand of how the story could have gone.