All S70/70D and X70D cars with the new refresh (around April 2016) are actually equipped with a 75 kW battery. You can upgrade the functional use of the battery to 75 kW 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.
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 service to see if it might still be available.