This is the recommended procedure for going live:

Step 1:
Document all settings from the Ingenico test-account and the Magento configuration.

Step 2:
Convert the Ingenico test-account into a live-account. Then configure everything as documented in step 1.

Step 3:
Use the test-Magento and check if everything still works. Use real credit card data now. The test-data (e.g. VISA 4 111 1111 1111 1111) will not work in live mode. You can refund the money afterwards. If it doesn't work, please ask the Ingenico support-team to check the payment methods and settings in the Ingenico-account. Keep in mind: at this point you are still using the test-Magento.

Step 4:
After everything has been fixed, test again on the test-Magento.

Step 5:
If all tests in step 3 were ok, clone all settings from the test-Magento to the live-Magento. Enter SHA-IN, SHA-OUT and the API user password in Magento again and save the settings.

Step 6:
Change the feedback-URLs in the Ingenico-backend from the test-Magento URLs to the live-URLs. If you are uncertain about the correct URLs, please check the documentation. Everything is explained there in detail.

Step 7:
Test everything on the live-Magento again.