Bringing a website back to life

Hello,
Since I started uni (and especially because this uni is abroad), I left some websites without any kind of supervision. I left them on a slow and cheap webhost, just hoping that they'll survive.
Well, you can guess what happened! They are dead! One website has A TON of articles about many things and I would like to concentrate more on promoting it and changing parts of it rather then on writing completely new content.
The other website has few pages of content and is, of course, as dead as it can be.
Furthermore, I will definitely change the webhost, but if I move the sites as they are on a new webhost (so, if I change their ip) will they be penalized (even more, god dammit) for duplicate content?

I think that you will not be penalized...but you know, nothing is sure in this business

No, it will not get penalized for changing the hosting but you need to mind the chance of content duplication problem

Clean them up. If they're total trash, just put a one-page keyword-focused landing page on a brand new host. Do standard SEO on the landing page: H1 with your keyword, 350-600 word article, an image, etc. Let it sit there for a few weeks. Then build a new site with good content and solid onpage SEO.

It will work fine.