Answered by Shaykh Hamza Karamali, SunniPath Academy Teacher
What is the Shafii position on making up missed sunna prayers such as tarawih?

In the Name of Allah, Most Merciful and Compassionate
The Prophet (Allah bless him and give him peace) said:
“Whoever sleeps through a prayer or forgets it, let him pray it when he remembers it.” (Bukhari, Muslim)
There is also a hadith in Bukhari and Muslim that the Prophet (Allah bless him and give him peace) made up the two post-zuhr sunnas after salat al-asr.
The Shafiis have inferred from these and other hadiths that it is recommended to make up any sunna prayer that is prayed at a particular time [nafl mu’aqqat]. Imam Nawawi said in Minhaj al-Talibin:
“ and according to the stronger position [ala al-adh-har], if a supererogatory prayer that is prayed at a particular time is missed, it is recommended to make it up.”
Al-Khatib al-Shirbini commented that this recommendation to make up a missed sunna prayer of a particular time remains forever. So, for example, if one missed the two sunnas before fajr, it would remain recommended to make up these sunnas even if years pass by without one doing so. Similarly, for tarawih, if one missed praying it on a particular night, it would remain recommended to make it up for the rest of one’s life, even after Ramadan passes.
(Mughni al-Muhtaj, 1.342).
And Allah knows best.
Hamza Karamali