Try to modify your search to:
Something
([^‰\r\n]*)
Something Else
This should 'capture' what's inside the brackets and store it in a variable, $1
.
Then, try this replace:
Something
<Tuv Lang="EN-US">$1</Tuv><Tuv Lang="PT-BR"> </Tuv>
Something Else
I can't say if this will work I jEdit or not since I don't have it through.