Ubuntu :: LibreOffice Regex - Replace [:alpha:]$

My friend lost her dissertation and she had only a pdf copy of it. I am trying to convert the pdf into an odt format. After copy-pasting the content into an odt, i need to replace all paragraph breaks which are not following a dot with a space. For which i thought of using the regular expression feature of Libre Office. I've not succeeded so far.

I tried: to replace [:alpha:]$ or [a-z]$ or [a-z]>$ with space, but none of them worked. Finding [a-z] seems to work, finding [a-z]> too. So did finding $ (end of paragraph) but if i combine any regex with $ then it doesn't find anything.