I would like to ask whether I can use "which" twice in the following sentence:
We are so (so!) excited for our big day which is just around the corner and which would be meaningless without you!
I would like to ask whether I can use "which" twice in the following sentence:
We are so (so!) excited for our big day which is just around the corner and which would be meaningless without you!
As a conjunction has been used, there is nothing wrong with the sentence in terms of the repeated use of which.
Stylistically, you probably want to put a comma before each instance of which:
We are so (so!) excited for our big day, which is just around the corner, and which would be meaningless without you!
At least in US English (but not UK English), if the information is restrictive (if you don't use a comma), you normally use that rather than which. Doing so here would make the sentence look like this:
We are so (so!) excited for our big day that is just around the corner and that would be meaningless without you!
However, aside from the issue of which or that, with or without commas, the repetition of the word itself is fine.