Absolutely. You are more than welcome to upgrade to any of our new plans at anytime.
You can upgrade by loginging into your client area and going to Web Hosting >> Choose your Hosting account >> Upgrade / Downgrade account.
You can still stay on our legacy CX, EX, LX, or DX shared plans or our SR, CR, ER, LR and DR reseller plans. These will always still be active for customers on those plans, but we cannot downgrade or upgrade from any of those plans anymore as they are not active.