Code for Replaying a Game w/o Restarting it?

Hi I made this game just for the fun of it:

Code:

#include <stdafx.h>
#include <iostream>
#include <cstdlib>
#include <time.h>

using namespace std;

int main()
{
	const int lowest = 1;
	const int highest = 999;

	int nNumber, nGuess, nNoOfGuesses;

	time_t seconds;
	time(&seconds);
	srand((unsigned int) seconds);

	nNumber = rand() % (highest - lowest + 1) + lowest;
	
	cout<<"Guess the Number - by UPNPAD" <<endl <<"Hey you! Lets play guess the number! Okay, the rules are: " <<endl;
	cout<<"1. The number is anything from 1-999" <<endl <<"2. You have 10 guesses to get the number" <<endl; 
	cout<<"3. If you get it wrong, I'll tell you if you should guess higher or lower next  time." <<endl <<"OK! Let's Play!" <<endl;
	for (nNoOfGuesses = 1; nNoOfGuesses < 11; nNoOfGuesses++){
		cout<< "Please type your guess: " <<endl;
		cin>>nGuess;
		cin.ignore();
		if (nGuess < nNumber){
			cout<<"Try guessing higher." <<endl;
		}
		else if (nGuess > nNumber){
			cout<<"Try guessing lower." <<endl;
		}
		else if (nGuess = nNumber){
			cout<<"Well done! You guessed correctly!" <<endl;
			cin.get();
			return 0;
		}
	}
	cout<<"You didn't manage to guess the number in 10 tries. The answer you needed was " <<nNumber <<"   :( Better luck next time!" <<endl;
	cin.get();
	return 0;
}

I'm wondering how, after I either win or lose at the game, I would give an option to restart the game. Possibly a switch case? And how would I define the replay point in the game?

Sure, put the game itself in a loop. There are several thousand threads about this, generally involving doing so incorrectly looking for yes/no replies.

Play 1 game

Code:

int main ( ) {
  playGame();
  return 0;
}

Play several games

Code:

int main ( ) {
  do {
    playGame();
    cout << "Play again? ";
    cin >> answer;
  } while ( answer == 'y' );
  return 0;
}