Дописываем после RewriteEngine On
Вариант 1
RewriteCond %{HTTPS} =off
RewriteRule (.*)
https://%{HTTP_HOST}%{REQUEST_URI} [QSA,L]
Вариант 2
RewriteCond %{SERVER_PORT} !^443$
RewriteRule .*
https://%{SERVER_NAME}%{REQUEST_URI} [R,L]
Вариант 3
RewriteCond %{ENV:HTTPS} !on
RewriteRule ^(.*)$
https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
Вариант 4
RewriteCond %{HTTP:X-HTTPS} !1
RewriteRule ^(.*)$
https://%{HTTP_HOST}/$1 [R=301,L]
