All S70/70D and X70D refresh vehicles (around April 2016 and after) are actually equipped with a 75 kWh battery pack. You can upgrade the functional use of the battery to 75 kWh for a one-time $3,000 fee. This increases the range of an S70 from 230 to 249 miles. The S70D changes from 240 to 259 miles. (Feb-2023 update)
This upgrade is done in software and does not require a service visit.
As of 2019, Tesla appears to have discontinued this program. You’ll have to contact Tesla service to see if it might still be available.