I can find empty paragraphs with ^$ but there’s no way to replace a single paragraph break with two before pasting stuff online to our Web site. Word lets you do this with ^p and AltSearch works with \p but the Find & Replace dialog in LibreOffice Writer finds the character p followed by a space instead of a paragraph mark/break.
Did you check the option for Regular Expressions?
To expand on this answer, if you do a regular expression search for ^$ and replace it with \n\n that should work.
Same question. Regular expressions enabled, tried ^$, \p and so forth. Does not work.
^$ would only work if it was a blank line – two paragraph returns, right? Need to select the “end of paragraph” non printing character ¶ – (U+00B6)
Do you want to add a blank paragraph after of each non-empty paragraph?
Find .$ (dot-dollar)
Replace with &\n (ampersand-backslash-n)