Just so you know, only those paid orders that haven't expired can be renewed.
Step 1: Go to GoProxy Dashboard.
Step 2: Find "Static Residential Proxies/Datacenter Proxies" under "Use Proxy" tag in the left function bar.
Step 3: Click "My Plans", drag the bottom bar to the right, and choose "Renewal" under "Action" of the order you want to renew.
Step 4: After you complete the payment, your plan will be renewed, and you can find your renewal order in the path below:
GoProxy Dashboard - Billing - Transaction - Renew plan.