Don't use pcre in redirect. For what you ask you just need a simple: Redirect / https://yourdomain/ in the nonssl virtual host.
If you insist on using pcre with redirect for some particular reason you have not mentioned yet, use RedirectMatch. Won't that redirect all traffic? I only need to redirect http://share traffic to https://share.domain.tld/share. Maybe this is where, as you mention, to use redirectmatch?
