There's nothing wrong with it in my opinion, speaking as somebody who rebooted after a long absence. Of course, in my case, the gap was much longer and webcomics have changed a lot. I've also moved from Smackjeeves and a (now long dead) dedicated site to Tapas.
My current comic, Errant, which I started a few months ago, is a reboot of a comic I drew about ten years ago called Fan Dan Go.
I thought more of my readers would be people who remembered the old one, but in actuality, the vast majority of people are totally new, and old readers don't really remember the old one well enough for it to have much impact on the new comic. Like at most they remember it's about knights and there's a character called Rekki. It suits me fine because I've taken the story in a very different direction this time. It's effectively a new comic with some legacy features that old friends can enjoy.
My advice is to just approach it like it's a new comic, and do it because even if you weren't quite ready to tell it back then in terms of time, skill, planning etc. there was still something about the characters or story concept that you feel like you could still use to make a good comic. I think after five years, the few old readers who are still regularly on tapas won't mind the reboot because they'd need to refresh themselves by re-reading the original anyway before continuing, and new readers will be starting afresh.