I think CGI.pm could do it for you, it has parameters to auto-fill in submitted values (not only checkboxes). You should read the documentation for it.

But just focusing on your code, you could simplify it a lot. First, use a subroutine. (Note that the description for a checkbox should follow the checkbox, but I made it fit your code)

    sub checkbox {
        my ($name, $value, $sel) = @_;
        my $checked = ($value eq $sel) ? "checked" : "";

        print <<EOT
    $value: <input type="checkbox" $checked name="$name" 
        value="$value">&nbsp;&nbsp;
    EOT
        return ($value eq $sel);
    }
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This way, you can write your first two if statements like this:

    checkbox("ss", "ss", $ss);
    checkbox("ss", "ssd", $ss);
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Next, you could replace the first three if statements by

    my $found = 0;
    CHECKBOX: foreach (ss ssd pers) {
        if (checkbox("ss", $_, $ss)) {
            $found++;
            last CHECKBOX;
        }
    }
    if (not $found) {
        # code for those checkboxes with special treatment
    }
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Of course, the code could be more simplified, but I leave that as an exercise to the reader. ;-) (No, actually, you will have to do it yourself because I don't know your problem.)