The loop length upgrade is a little unnecessary, because if you just move the cursor fast enough, the segments can be far enough apart that you can draw a loop around the entire screen. This is possible at the start of the game.
I understand that upgrades and buttons only appear after a number of points are accumulated, but you should consider disabling them instead of hiding them and telling the player how much points are needed to "unlock" them. You don't have to tell the player what the button does (replace text with "???" etc.), only that there is more content. Otherwise the player doesn't really have much incentive to keep gathering points, because it's ambiguous whether there is any more content.