At schools like MIT or Caltech are you allowed to update standardized test scores, subject tests, portfolio, and or letters of recommendation if you apply to early admission but get deferred?
I don’t know about those schools specifically but that’s pretty much what schools expect you to do if you’re deferred - beef up your application and try again.
You can always send more material. Colleges look for a continued level of interest.
1st semester grades,new tests and an update of achievements-- not new rec letters or essays