Major changes are coming to Rocket League, including new XP, progression and clubs systems. The initial update is coming August 29 to all platforms, with Rocket Pass, a time-limited item unlock system, launching the following week.
The update will remove the previous level 75 cap and players who have continued earning XP through online matches beyond that level cap will be taken to an even higher level based on the XP they would have earned. In addition to this, the amount of XP needed to progress between levels is being flattened.
Source: IGN.com Rocket League Will Soon See Big Progression Changes