Actually there is another way to play your free spin, For example your balance is 1000 Satoshi then you have to increase your bet to 1200 or more and then spin
your bet must exceed your balance then the spin will fail/invalid because the balance is insufficient then you will see new free spin.
What I have noticed recently that no need to refresh the page to play free spins. If first round end then try to make another bet with real money, you will see a pop up that you can not bet due to you have left some free spins.
So It's now less annoying to play than before.