The 100hrs is only on the RX 480 and GTX 1070 plan.
AMD Radeon RX 5700 = 63 Hrs
AMD Radeon RX 5700 XT = 46 Hrs
Nvida GeForce GTX 1080 = 53 Hrs
Nvida GeForce RTX 2080 Super = 35 Hrs.
As Finatik metioned, when put money into your account, you should automatically see the $35 credit. Remember, the account doesn't show you how many hours you have left, it shows you how much money you have left. So you should see $40 minus the time you've already spent.