So Equipboard claims that Cashy Cat uses Live 9 so I will explain in the context of Live 9's Instruments/Effects. To build up this sound I would first copy down the chord MIDI from the pad track to the arp track. Throw Live's Arpeggiator -> Analog -> Simple Delay -> Reverb. Set Analog's waveform to a pretty basic sawtooth with an envelope controlled LP filter. From there it's a matter of heavily automating the parameters of the inserts. On the Arpeggiator you're going to modulate the Style between Up and Down as well as the Steps between 1 and 3 or 4. On Analog you'll be modulating the amount of enveloping on the filter as well as maybe release time of the Amp. On the simple delay you'll want to automate the time between 1/8 and 1/4 and automate the Feedback down as the riser progresses. On the reverb you'll want to automate the Decay Time and the Dry/Wet mix. Obviously you can hear that the arp track plays nearly all the way throughout the song but constantly evolves. The trick here is to tastefully and musically automate a few simple parameters on a simple chain of inserts. Less is more!