Aspose.Cells for JasperReports requires a .jasper file to be filled to a .jrprint or a JasperPrint object before it can be exported to XLS file. There's no modification needed for the jrxml file whatsoever. The filling procedure will store internal representation of charts into the JasperPrint object, which will then be used to generate editable charts.
Please read JasperReports' document for detailed description of filling a report.
Here's an example:
JasperPrint jasperPrint = JasperFillManager.fillReport(jasperFileName, parameters, getConnection());