What empiric dose change, if any, do you make for patients already taking liquid or softgel levothyroxine preconception upon confirmation of a positive pregnancy test?  

Based on the Alexander et al., PMID 15254282, it is recommended to increase Levothryoxine from 7 to 9 tablets/week and check TSH and Free T4 when possible. Repeat TFT should be checked every 4 weeks until after 20 weeks of gestation with T4 adjustment to keep TSH.