If you used the online version of TurboTax for your 2018 taxes, then log in using the same login credentials you used last year. It will be automatically imported for your 2019 tax return if using the online version.
If you used the CD version of Turbotax for your 2018 tax return and are using the CD version for your 2019 taxes, then make sure your .tax2018 file is in the documents\turbotax directory "before" you start your 2019 tax return. You'll have the option to import the data from the 2018 tax file then.
If you did not use TurboTax at all for your 2018 return and all you have is a hard copy printout of the 2018 IRS Form 4562 from your 2018 return, then y ou'll have to enter all of the asset data one keystroke at a time, regardless of what version of TurboTax you are using (online or CD)