I think I have the same issue here but not for the pinterest button.
I use Really simple share buttons with infinite scroll and when the next page is append, the buttons are not showing anymore.
I use Fb / Twitter / LinkedIn / G+ and mail buttons
I found a fix : http://stackoverflow.com/questions/10212686/social-icons-not-working-with-infinite-scrolling-on-wordpress/10458205#10458205
My problem is I tried to do the same with the LinkedIn Button but I couldn't make it works so if one of you could tell me how this work because I don't have any idea !
You can see it in action : http://www.jaimelesstartups.fr
My guess is I have to deal with the LinkedIn API but I couldn't find the syntax to make LinkedIn parse my element again.