When you "Like" a post, it's shown on your profile that you liked it, so it works as a "re-memo". If you want a text linked to the "re-memo", you can "Reply" instead.
What would "re-memo" actually do? Just a repost so your followers see it? I guess it could be just a link to the TXID of the orig memo, & you could put a small amount of addt'l text.