Please solve the programming task below using a self-contained code snippet in a markdown code block.

You are given a numeric string num, representing a very large palindrome.
Return the smallest palindrome larger than num that can be created by rearranging its digits. If no such palindrome exists, return an empty string "".
A palindrome is a number that reads the same backward as forward.
 
Please complete the following python code precisely:
```python
class Solution:
    def nextPalindrome(self, num: str) -> str:
```