Booberfragless is correct about the new episodes not airing until Sept. or Oct. The reason lies with PBS, not completely with SW. This article can help explain a little bit:
http://www.kidscreen.com/articles/magazine/20060101/mtots.html?word=pbs
I believe decisions are still being made as to which episodes they are airing to fill the void.
As for the "flashback" to Miles' first day of school, that's not exactly correct. There will be a scene showing Gabby and Miles' first day of kindergarten, but it's not an old clip.
Unfortunately, Booberfragless is correct and more details are still considered "confidential" so I can't expand much more.