If you don't take (and pass) all three steps within 7 years of taking Step 1, your "sequence" is null and void, and your scores are unreportable.
You then must start over and take all 3 steps again, earning all new scores - assuming, of course, you haven't given up on getting a medical license in the meantime.
Way too much work to even consider as a means of upping a score you're unhappy with.