Express Billing Updates

Has anyone created an upload file or Excel to CI that allows for quantity and unit amount updates to invoices in express billing for multiple invoices? We created a custom upload process to update PS_BI_LINE and recalculate the net extended amount, but the process will time out if there is more than approximately 100 invoices in the file, or a single invoice that has more than 100 lines on the invoice. We also tried to use the delivered Excel to CI functionality and had the same result. Does anyone have a work around or solution that they