Two other things you can do, which are more in keeping with the 'no deletion' guideline (although I can't imagine anyone complaining about that in a social game thread, it might be an issue with something in P&R or Elliquiy U.)
1) Use bookmarks. This way, you proactively choose which threads you want to keep an eye on, and you can see the list even if you've recently read/posted. I find this indispensable with RPs where I might read a post and be unable to properly phrase my response for a few days.
2) Before hitting the 'Show new replies', hit the top level of the socialization forums, read the new ones that you feel like reading, and then hit the 'Mark all as read' for that section of the forum.