I need to know please how can i reset my android 4.1.2 symphony xplorer without deleting it's game data
That would be a contradiction in terms: to be a "reset", it has to delete all your data. What you need to do is back up your game's data first, then do the factory reset, then reinstall the game, and finally restore the game's data from a backup.
This is easiest to do if your device is rooted: you can use a backup app such as Titanium Backup to backup and restore any app's data.
If you don't have root, then other apps can't access your game's data to back it up. If the game supports Google's automatic cloud backup, then that will work without you doing anything (though it's known to be buggy on some devices, when the manufacturer or carrier has customized/replaced the backup transport).
If the game doesn't support that, or you can't or won't use Google's backup for whatever reason, you can still back it up using
adb, by following these instructions.