Stevenson had made 24 appearances but had been dropped to the bench for the last four games and moves to Kirkcaldy until the end of the season.
Striker Nade, who is also 32, had played as a trialist with Annan Athletic in League Two after being released by Stranraer in November.
He had moved to the Scottish League One club from the Sons in the summer.
The Frenchman made 12 appearances for Stranraer, scoring twice, but had scored seven times in 14 games for Dumbarton last season.
Stevenson had joined the Sons after helping Ayr United win promotion from League One last season.
Joe Thomson has also left Dumbarton, the midfielder returning to Celtic at end of his loan spell after making 24 appearances for the Championship club.
Meanwhile, fellow 19-year-old Ryan Hardie has joined Rovers for a second loan spell from Rangers, having scored six times in 12 appearances in early 2016 and then scoring three in 17 games on loan at St Mirren later in the year.
He and Stevenson were on the bench for Monday's Fife derby at home to Dunfermline Athletic.
Ryan Stevenson has joined Raith Rovers, with Dumbarton having re-signed Christian Nade as his replacement.