The party says it would scrap the upper chamber in favour of a democratically elected second house where laws are ratified.
"We're looking at constitutional reform and when it comes out as you'll see from our manifesto, what we want to do is make sure we have a voting system that makes sure that people's voices are represented," said the party's deputy leader Amelia Womack on Premier's News Hour.
"We want to abolish the unelected House of Lords and have a more democratically representative body in that position, and those are important parts in terms of looking at a fresh constitution for the country," she added
On Wednesday, Labour defended plans to close a tax loophole for wealthy people who earn their income overseas.
The party's announced it'll end non-dom status if it wins power.
The Conservatives, meanwhile, said children who don't get a good pass in Sats tests will need to resit the exams if they win the General Election.
Ministers believe too many pupils are going to secondary school in England with substandard reading, writing or numerical skills.
