I wanted to help my girlfriend format her thesis. Unfortunately, she simply wrote out her bibliography and so you have to keep the references and order right all by manually.
Is there a way to import/convert this to in-document bibliography entries or entries in the bibliography database. So that I can simply generate and automatic bibliography?
At first, I thought I could simply parse the text into a bibtex format. But I don’t see a way to import bibtex into LibreOffice.
Oh dear … her supervisor might have gently suggested that reference management begins when the work on the thesis begins! 
Bibliography management can be handled natively, although as @bencomp notes, this doesn’t provide for automating imports, and you will need to ensure that Base is installed. (Sometimes it isn’t, depending on platform.)
As for alternatives, the first thing that comes to mind is Zotero with LibO, although there are several other options available. See also the “is there a bibliography tool?” Q&A for further possibilities.
(Since you’re familiar with bibtex, you might also generate the bibliography externally to LibO, but that’s well beyond my experience and competence.)
Updated to clarify process envisaged by OP.
Well, her supervisor didn’t say anything and I suppose she also doesn’t know much about the tools 
So, it seems like there is not real way to fix this… I will check out Zotero, but now that I have seen the amount of works cited and the time left, I think I’ll have to leave it at that…
No, it is not possible to create a database-based bibliography from a bibliography in text using LibreOffice. There are tools that can parse written citations and create a file that can be imported into reference management software, although I don’t have any experience with any and therefore can’t really advise.
@dajare’s suggestion to use Zotero and the plugin for LibreOffice may help. If you manage to parse the bibliography into BibTeX, you can import the file into Zotero and insert/edit (in-text) citations and insert/edit (end-of-text) bibliographies using the plugin.
If that fails, you could try to find each cited document online. Zotero can import metadata by the publication’s ISBN or DOI, but it is also often able to import the publication metadata from the publication website. It requires manual work, but saves a lot of copy/paste.
There are zillions of metadata extractors. See http://stackoverflow.com/questions/1781672/convert-bibliographic-references-from-a-document-into-bibtex-or-endnote for the further discussion.