First, try this in replace all mode:
Code:
(?<=[\p{Ll},;]) *</p>\s*<p class="[^"]*">(?=\p{Ll})
, replacing this with a space.
Then, remove (?=\p{Ll}) part, and do manual replacements troughout the file.
Then, restore that part, and remove the (?<=....) one; continue replacement with manual confirmations.