For a Roth IRA for which you contributed funds directly in to the account (not a conversion from a t.Ira) you may withdraw your contribution at any time, no penalty. Attempting to withdraw any earnings from the contributions will see penalties if you are 59 and under.
So in your case, you contributed $5500 in to the account. Say the value goes up to 5700 from investments. You may, at any time, withdraw up to $5500 from the account in the future.
Say in 2017 you contributed $5500, and for 2018 you contributed $5500, then withdraw $5500. You can re-contribute up to a year's worth of contributions 5500 and it's still good. If you had withdrawn $6000, you may only re-contribute up to $5500, and the 500 is removed from your contribution total for the account.
Rothira.com Returning Withdrawn Contributions