You should make use of relative data paths. For example, regardless of where your application directory is, you should have an data subdirectory. Then, in your path statement, you can set path to data. From that point on, you don't need to worry about explicitly specifying the path when opening data.

Of course, you will want to make sure you have an error handler that will deal with missing data.

Alternatively, you could have an options screen for your application that specifies your data directory and use that directory in your path statement. Personally, I like the first approach.