New to regex find and replace!

i'm sure for some people this is cake, i just have no clue how to get this regex to work correctly. i have 1000 snippets of code that look like this:

<p class="indent-arrow"><span class="_idGenBNMarker-1" lang="en-US" xml:lang="en-US" xmlns:xml="http://www.w3.org/XML/1998/namespace">1. </span>A BUNCH OF DIFFERENT TEXT FOR EACH OF THE 1000 POSTS</p>

I need to change the beginning and ending text to this without harming the text for each post:

<p class="bullists"><span>1. </span><span class="CharOverride-5">A BUNCH OF DIFFERENT TEXT FOR EACH OF THE 1000 POSTS</span></p>

i found a snippet of code earlier that showed i can place (.+?) in place of the post text in the search box. It successfully caused the search to find and highlight every single post perfectly, but it doesn't replace correctly. instead it replaces the post text with (.+?) ...i'm so close, but i know i'm missing something. can anyone help please???