Using Controller_Template I assume?
Not a problem, in your method you can just assign a new View to $this->template. Note that if you had assigned variables to the old template in your before() method, those will be lost.
I'm not too sure how to assign a new view to $this->template, I tried $this->template = 'dashboard', dashboard is the name of my template. But it seems no being the good way.
edit: found out $this->template = \View::forge('dashboard');
Correct.
If $this->template is a string, the Controller_Template's before() method will convert it into a View object for you, but that only works for the initial template.