Hey, @TK-1 .
Thank you for reaching and posting this question!
We’re delighted to hear that you were able to get some help from @deepaksharma , and the pagination is now working on the fresh theme. You should be able to work on the fresh theme without interrupting the older theme, and many of the elements (eg. collections, pages, blogs) do not need to be recreated - simply add them to the fresh theme. Once the fresh theme is complete, you can simply publish the theme to replace the older one.
If you have any other questions on this topic, then don’t hesitate to let us know.