If you get your variable name right (continuar, repeat, etc), then your code actually works fine:
#include <iostream>
#include <stdlib.h>
using namespace std;
int main()
{
char repeat;
int age;
do
{
cout << "ENTER YOUR AGE " << endl;
cin >> age;
system("clear");
cout << "would you like to repeat? (Y) or (N)" << endl;
cin >> repeat;
system("clear");
} while (repeat == 'y' || repeat == 'Y');
return 0;
}