Ah hah - that makes it really easy. Instead of doing:

print header;
print start_html("Thank You");
print  ("<Center>");
print ("Thank You ", param('RespName')," for your responses.! ", "\n <
+/center> \n<BR>" );
[download]

do

print "Status: 302 Moved\r\nLocation: $next_page\r\n\r\n";
[download]

and nothing else. This should instruct the receiving browser to move to $next_page. You might or might not have to output HTTP/0.9 302 Moved\r\n before that too, in the case of a redirect, depending on whether your web server handless that or not.