theducks's suggestion is, of course, perfectly fine, however, if you want to merge sentences, you might find this extended expression helpful that I use to merge sentences:
Find: ([[:lower:]],*;*:*)</p>\s+<p[^>]*>\s*([[:lower:]])
Replace: \1 \2
This expression will search for:
- a single lower case character followed by zero or more commas, semi-colons or colons
- followed by </p>,
- followed by one or more white-spaces (including line-breaks),
- followed by <p> (with optional attributes),
- followed by zero or more spaces and a single lower-case character.