I didn't quite get what you were refering to and couldn't try it.
I've now had a chance and by changing it to:
<p class="heading">(.+)</p>\n\n <p>
and replace with:
<p class="heading">\1</p>\n\n <p class="newscene2">
it seemed to work.
This found the instances and made the correct replacement without effecting the text in the heading.
Thanks very much for this.