If you are using a "program-described" PF to hold .CSV data, there is no way to increase the length. A new version must be created. Just rename the old one and create a new one with the original name and with the new length.
Copy any data that you need to retain.
There shouldn't be any logicals to be concerned about.
Also, if this is really for .CSV data, it probably shouldn't be in a PF. It should be in a streamfile somewhere under the /root file system. There wouldn't be any issues with lengths in that case.
Actually I donot have a Source for this CSV file. its program described PF.
I have created the new file and copied the data.