I've used this to replace line feed characters annd assume it would work for other characters too:
In the export, export the field to a Temp001$ variable using the operation Assign.
In the Calculation field for Temp001$, enter SUB(table.field,""."","""")
A period in the middle set of quotes, and nothing in the last set. Without testing, you might have to convert the number to a string value first before applying this sub formula.