I got a 1600 on the SATs but I want at least a 2000. Is it possible to bring the sat score up by 400 points in two months? I’m only planning to take one more day but is that enough or should I take another one before my last one?
Hmm it’s a stretch but it’s possible. Depending on your subscores and your strengths and weaknesses, work to improve every aspect. Don’t overload yourself to the point of burning out but you definitely need to study and actually retain the information/basics.
I went from a 1580 on the PSAT to a 2000 on the SAT. You can definitely go from a 1600 to a 2000. You do have to put in a LOT of effort, however. I’m confident you can do it, though! Good luck 
I suggest you visit the test prep section of the forum. the SAT prep forum has tipped pinned to the top.
That is unlikely, unless you were having an unusually bad day the first time (due to illness, for example).
http://professionals.collegeboard.com/testing/sat-reasoning/scores/retake
“On average, juniors repeating the SAT as seniors improved their combined critical reading, mathematics, and writing scores by approximately 40 points.”
Only 55 percent of test-takers improve their scores at all on the second try.
35 percent have score drops.
I echo what everybody else says. It’s possible, but you should not begin constructing your college list based on an unlikely scenario. You need to consider colleges where you can get in with your existing stats.
You need t construct your college list for schools with averages in the 1600-1800 range. If you score 2000, then you’ll have a shot at merit scholarships and you’ll be able to add reach schools, which is the easiest part anyway