Some questions about transferring

I am planning to try transferring into US university because I recently just failed miserably at doing so. And I was wondering about some things.
Firstly, if I am trying to transfer into the same school which I have applied to before, do I have to re-send my scores (SAT, TOEFL, etc)?
Secondly, are SAT scores important in the transfer process? (I am planning to re-take it if it is considered important.) Or should I just focus on my current GPA?
Lastly, how many schools should I consider applying to?
Just for some context, I am currently attending an international college and my best old SAT score is 2160 regardless of superscore or not.
If there are threads which already answer these questions, I would be grateful if I can have the links to said threads.
Thank you for your replies!

If you have been rejected from a university already, it is probably not worth reapplying. What will change in one year that will make you a stronger candidate. I suggest you look for 4-5 other universities (and not all of them should be the highly selective ones which only take a few percent of the transfer applicants) which have the majors you want and have reasonable acceptance rates for transfers (you can find this information with a simple internet search).