Haleivi what is the full 18 brochos fixing?
Tosafos is not actually referring to Friday Rosh Chodesh specifically. He is talking about any Rosh Chodesh when the following night is not Rosh Chodesh. He says there is no point in Davenning what you already Davened since you won’t be replacing the lost Yaale Veyavo, anyhow. That was in contrast to missing a Tefilla, totally. Even if the Tefilla you missed was a Shabbos Mincha while the Tashlumin Tefilla will be a Chol Tefilla, you are at least replacing a Tefilla for a lost Tefilla.
It seems from the argument that Tosafos holds the same about missing the Hazkoras Shabbos by Shabbos Mincha. There is nothing gained by Davenning another weekday Tefilla. (Obviously, if someone said the Shabbos Mincha without Hazkoras Shabbos, he actually didn’t Daven, so that’s the same as missing it.)
What I wrote before was a misrepresentation of Tosafos. Sorry about that.