During the Eid prayer I laughed because of something a little girl did. It was a very quiet laugh. Do you know if I have to make this prayer up? Should I make it up at home?
As much as I made research and knows, the Salah o Eid-Fitr is considered as a Wajib (obligatory) Salah from the viewpoint of Sunni brothers (by its conditions…), although it is not counted as a Wajib practice from the viewpoint of Shiite, haply Shiite consider it as a Mustahab or recommended Salah.
On the other hand, regarding laughing during Salah, (I'm not sure concerning the perspective of Sunni, but on the whole, from the perspective of Shia, laughing loudly would invalidate the Salah, but laughing slowly (not loudly) doesn't seem to invalidate it. (Beside, being advertently or inadvertently would be effective in it as well)
Apparently it is not necessary to make it up as @Ozbak (as a Sunni brother) mentioned it as well.