On screen, she was last seen setting out for new adventures in the pocket universe known as E-Space ("Warriors' Gate"). Although an older Romana was later seen in London in either 1973, 1993 or 2013 in "Dimensions in Time", dialogue within the minisode indicates this wasn't the real Romana. In the Big Finish audio dramas, Romana eventually returns to "N-Space" ("our" universe) and becomes Lord President of the High Council of the Time Lords, though she also spends some 20 years as prisoner of the Daleks. ("The Apocalypse Element" (audio story)) before being rescued by the Sixth Doctor. She went on to spend many years serving as president, both on Gallifrey as we know it and several alternate-timeline Gallifreys, and these exploits are depicted in the long-running Gallifrey audio drama spin-off series. During this time she worked alongside Leela, and also encountered a version of her first incarnation, as well as a future incarnation known as "Lady Trey" (played by Buffy actress Juliet Landau, who was cast to fill the gap left by the death of Mary Tamm).
In terms of current events in the TV series, her current whereabouts with relation to the Time War and Gallifrey's status post-"The Day of the Doctor" have yet to be revealed.