The 59-year-old talk show host and the 44-year-old actress are reported to be planning a lavish ceremony in Australia - where Portia was born - to celebrate their 10th wedding anniversary in summer 2018.
The couple are said to be keen to renew their vows in front of friends, family and celebrity guests, including Hugh Jackman and Deborra-Lee Furness, Oprah Winfrey, Reese Witherspoon, Jennifer Aniston, Pink and Julia Roberts.
A source told Australia's Woman's Day magazine: "They're recreating the beautiful wedding they had in 2008 with a few new twists.
"This second wedding will be a fresh start for them. They're so in love."
'Arrested Development' star Portia and comedienne Ellen have been together since first meeting backstage at an awards ceremony, in 2004.
The couple - who are both fierce campaigners for equality and GLBT rights - tied the knot when gay marriage became legal in an intimate ceremony at their Beverly Hills home in August 2008.
In 2010, Portia legally changed her name to Portia Lee James DeGeneres.
Celebrating their ninth wedding anniversary this summer, Ellen wrote on Instagram: "@PortiadeRossi and I got married 9 years ago today. Being her wife is the greatest thing I am. (sic)"
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