Notepad++ Remove New Line Pattern – Find & Replace Command

I want to remove a new line created after each name in a chat log file. Example:

Person1:[space]
their message
Person2:[space]
their message

So I set it to extended search in Find & Replace, and I search for the string:

: \r

And set it to replace with:

:[space]

It finds the instances of this that I'm looking for, but for some reason it doesn't bump the text back from the new line when I replace – and it says it's been successfully replaced. I tried removing the space from the replacement text, and it took the spaces out, but still didn't bump the text up a line.

Any suggestions?