To expand on fanfare's answer, lines 1 and 14 of the 2016 Form 8606 will have $5,500. TurboTax will do this automatically when you amend and enter the nondeductible traditional IRA contribution. The $5,500 from line 14 of the 2016 Form 8606 transfers to line 2 of the 2017 Form 8606 to be added to the $5,500 on line 1 of the 2017 Form 8606.
When amending the 2017 tax return with TurboTax, click the Continue button on the Your 1099-R entries page that lists your 2017 Form 1099-R reporting the distribution from the traditional IRA that was converted to Roth, and in the questions that follow indicate that you made nondeductible traditional IRA contributions for years prior to 2017 and enter the $5,500 of basis carried in from 2016 Form 8606 line 14. 2017 TurboTax will use this to complete 2017 Form 8606 as I described above. Also be sure to enter any year end balance you might have in traditional IRAs at the end for 2017 since this will affect the amount of basis that applies to the 2017 Roth conversion and how much basis remains in your traditional IRAs to be applied to future distributions.
