No, there is no way to redefine a class.
According to the C++ language standard the class definitions is:
class-specifier:
class-head { member-specification_opt }
The standard explicitly says that member specification should be complete within class definition:
Members of a class are data members, member functions (9.3), nested types, and enumerators. The member-specification in a class definition declares the full set of members of the class; no member can be added elsewhere.
Also the standard gives example of redefinition of class:
struct S { int a; }; struct S { int a; }; // error, double definition
is ill-formed because it defines S twice.