A method for effectively re-downloading data to a Field Programmable Gate Array (FPGA). The method uses two Complex Programmable Logic Devices (CPLDs) to implement control functions of Write-to-Non-Volatile Random Access Memory (NVRAM) and Write-to-FPGA respectively, in conjunction with a set of connectors with a detection circuit, such that according to a detection state output by the detection circuit to one CPLD implemented with Write-to-FPGA control function, a write-to-NVRAM operation for data is determined if the detection state is logic low and conversely data is written from the NVRAM to the FPGA.