Unfortunately no, you cannot currently do this directly, but we are considering adding this ability:
case=969
For now, have you considered prompting for the Project name, so use the Snippet:
#pragma once
#ifndef __{$PROJECT$}_$FILE_BASE_UPPER$_H__
#define __{$PROJECT$}_$FILE_BASE_UPPER$_H__
$selected$
#endif // __{$PROJECT$}_$FILE_BASE_UPPER$_H__
By using "$PROJECT$" instead of "PROJECT" VA will prompt you for the project name, which will then be inserted into the Snippet code. You do have to type in the project name manually, but only the once.