In customising the andreas1234567 code, you can use it as

    use strict;
    my $str = q{sometext with conetnst add kklkk&dfaf:dfaÜÄmlddö;};
    $str =~ s/&([^;]+);/&$1 ;/g; #This includes all the characters til
+l the semicolon
    print $str;
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Punitha