Well, you are storing CONVERT which was loaded at the beginning, before the loop, so that would only store once.
Inside the loop you are creating YourTable.
If you want to create several similar tables in a loop and store them individually, here's an example:
For counter = 1 to 3
Load $(counter) As loop_pass autogenerate 1;
Store Table1 into $(filename) (qvd);
Drop table Table1;
This will create 3 qvd files (x1, x2, x3)
As was said before, you need to drop the table in the loop before generating it again.