easy. bost the remotes signal. makeing the ariel longer will do that, but it will need more power. so, your gunna have to edit your remote to have a longer ariel and and to hold lots more batteries. here is a idea of how to match the energy to the ariel.
Jeremy Clarkson once demonstrated in the Top Gear programme that if you pointed the remote at the side of your head so it was touching your head and then operated it it increased the range quite a distance. I tried it with mine and it did excactly as he said!