以下是重构后的内容：

```csharp

using System;

class Program

{

static void Main()

{

string inputStr = "BDLINKQkRGUwADAAAAACAPgAAAACfKrZfyV0Q2NwcOKqyP1MU28yWh5JrJhfb+WcmfkatkiEAAABEAEEASQBTAEUATgBSAFkAQQBLAFUALgBQAEUAUgBGAEUAQwBUAC4ANAAuADAALgBwAGEAcgB0ADEALgByAGEAcgAAAIA+AAAAAF2beiYRd984mIFzxd/ynRg1by535rknS36ql4InivpzIQAAEQAQQBJAFMARQBOAFIAWQBBAEsAVQAuAFAARQBSAEYARQBDAFQALgA0AC4AMAAuAHAAYQByAHQAMgAuAHIAYQByAFsRXAgAAAAAVjjJy2jc8VbLsUSlbkc69Mq/aSATk/MdmYgi2WJm7SIhAARAABBAEkAUwBFAE4AUgBZAEEASwBVAC4AUABFAFIARgBFAEMAVAAuADQALgAwAC4AcABhAHIAdAAzAC4AcgBhAHIAAA==";

Console.WriteLine("原始字符串：");

Console.WriteLine(inputStr);

Console.WriteLine();

string decodedStr = DecodeBase64String(inputStr);

Console.WriteLine("解码后的字符串：");

Console.WriteLine(decodedStr);

}

static string DecodeBase64String(string base64String)

{

byte[] base64Bytes = Convert.FromBase64String(base64String);

return Encoding.ASCII.GetString(base64Bytes);

}

}

```

这段代码首先将给定的字符串作为输入，然后调用 `DecodeBase64String` 函数对其进行解码。这个函数接受一个 Base64 编码的字符串，将其转换为字节数组，然后将字节数组转换回 ASCII 编码的字符串。最后，程序输出原始字符串和解码后的字符串。