I’ve have taken 3 SAT subject tests, and I’m really satisfied with the results of 2 of my subjects. If i intend to retake the 3rd subject do i need to take all 3 of the subjects again?
No. You’d only have to retake the test you intended to.
So that means that I can send scores to colleges from different test dates? eg: my chemistry and maths level 2 scores in june test, and my physics scores in october test?
Yes except for schools that require you to submit all scores from all tests. E.g., Yale.