Google have said that if you have the same site at a different URL then they may apply the same penalty to the new site as they did to the old one, therefore if you wish to redirect a site, I would recommend doing it at the same as you make some other significant changes to it.
I came up with a way of doing this which should work.
On the old domain redirect everything to the home page and then on the home page create a noindex, nofollow page with the following line of code in it:
Where example.com is your NEW domain name.
This way you're using a redirect at the html level, but telling search engines to not index or follow the page. This should work!
