You should consider separating your interface file from your data. FileMaker developers commonly refer to this as the Separation Model. The idea is that you'll tend to change the data structure only once in a while, but scripts and layouts are frequently updated. By keeping UI and data in separate files, you can simply replace the interface file and not have to do any import at all!
If it's not feasible to do this, then you'll want to create a script to automate the import process.
Thank you Tom for your reply. Separation Model is new to me. I will look into it.