Here I'm inserting part[1] of the code. The same is copied in part[2] & part[3] with only changes with respect to month & year limits.

 
          if (time_pressed)		// for setting time
	   set_time_flag;
	 while(time_flag)		// here date setting is being done
         {
 up1:        if (up_pressed)		// is increment key pressed?
              { LCD_delay(200);		// temp1 to display tens place
                if(temp2>=9)		// temp2 to display units place
                 {temp2=0; temp1++;}	 
				
	     else temp2++;
				 
	     if (temp1>=3 && temp2>=2)  // don't allow date to cross 31
		{temp1=0; temp2=1;}	// reset to 01
				
		LCD_delay(200);
//              clr_up_flag;
                LCD_command(0x80);
                send2lcd(temp1);        // Show changed date on LCD : tens place
                send2lcd(temp2);	// Show changed date on LCD : units place
                
                if(up_pressed)		// is up key pressed?
                   goto up1; 
                if(dn_pressed)		// is down key pressed?
                   goto dn1;
              }          
 
 dn1:          if (dn_pressed)
              { LCD_delay(200);
                if(temp2<=0)
                 {temp2<=9; temp1--;}
				
		else temp2--;
				 
		if (temp1<=0 && temp2<=0)// reset temp1 & temp2
		 {temp1=3; temp2=1;}
				
		LCD_delay(200);
//              clr_dn_flag;
                LCD_command(0x80);
                send2lcd(temp1);         // Show changed date on LCD : tens place
                send2lcd(temp2);	 // Show changed date on LCD : units place
                
                if(up_pressed)		 // is up key pressed?
                   goto up1; 
                if(dn_pressed)		 // is down key pressed?
                   goto dn1;
              } 
           }