You can earn more IP via IP Boost. A way to get one for free for like 4-5 matches is verifying your email adress, otherwise you have to buy the IP-Boost in the Store under the Category "Boosts" I guess.
You can always bot yourself some referrals if you know what you're doing, or buy them from a service. Or you can just use a bot that plays co-op vs ai games that will get you free IP when you're not playing the game
