So basically I made this stand alone robe set, ironned out the bugs and trouble and now I'm getting feedback from the community. All's great, except I don't know how updating a mod works exactly.

What do I do if I want to add a new version of my robes with an enchantment to complement the set of robes already existing (in my mod)?

Not sure about Workshop, but Nexus, just package and upload your new version and document it in you read me and description. Also change the file version in your description options. I usually move the old file to "Old file" category, and make sure the new one is set to main file. I'll also post an announcement on my comments so it goes out in the forums.

Thanks for the answer, but yeah, I'm on workshop. I don't think my subscribers would appreciate me changing the mod every once in a while, forcing them to re-subscribe.

There's nothing preventing you from using both services. Personally, due to how they handle certain things I'm not downloading anything from the Workshop. I doubt I'll be uploading anything more than my simple Breezehome Tweaks either. There are likely others who feel as I, so if you want maximum exposure, in my opinion you should use both.

On steam, the only thing I did was to re-upload. It did not affect my few subscribers in the way that they did not need to re-subscribe. Technically, it reuploads your saved data, which means any changes you would have made to your mod since posting. The last suggestion is to save your text description on a notepad or word document because this will be put back blank in steam (at least in my case it does) every time you re-upload.

So basically I should re-open the .esp file and make my modification then re-upload it the same way?

Can I start another .esp with all the modification and up load that with the same name?

@Balok: I want to figure out steam first, then I'll probably get on the nexus.

Use the existing .esp as the active file, change it, save it, and reupload it - this will update the existing entry in the workshop as I have done it several times.

Oh thanks. It sounded too easy to me.

Nope. it's that easy. And like Dhomnick said, copy your description from the page first before you upload it because that whole thing is kind of borked at the moment. Copy it and paste it [or hold it in your clipboard] - upload the new mod then go directly to it and edit the details - putting the proper description back.