This is very very similar to the online casino "sticky bonuses". For a sticky bonus, you might deposit $100 and the casino will give you another $100, but you can never cash out that $100. That means, for example, if you bet it all on one hand, you will either win $200 (total balance would be $400, of which you could cash out $300, which is a $200 profit on your $100 deposit) or you'd lose your $100. If each has roughly a 50% probability, that one bet is worth $50 in +EV. If, on a win, instead of cashing out, you went for another double up, your total EV for the play would go up to $75, with a 25% chance of a $600 win and a 75% chance of a $100 loss. In general, the higher your target, the greater the EV (approaching $100, which is the limit for your EV on this play) and the less frequently you will win.
Aside from the fact that you have to front the money for this promo and you get the rebate at the end, it's very similar. You put up $100 and play it like a sticky bonus. You'll want to have a target of turning that into probably at least a thousand minimum (assuming you have a significant bankroll). Assuming you play VP, you'll probably want to use the biggest coin you can and target $1000 or more. This will have a high rate of failure (90%+) but you won't lose anything because you'll collect the $100 rebate. If the VP machines have a double up feature, you'll want to use an even bigger target, probably $2000ish or more (because you get more variance with no house edge). If the game had no house edge at all, the EV maximizing target would approach infinity, but because there is a cost to every hand you play, the optimum target is finite. That's why the target is higher if you have the double up feature. Similarly, the target should be lower if you are playing games with a higher house edge. I don't have exact numbers for the optimum targets, but I'm sure somebody here can calculate it. I'm sure there are some good references online for optimum play on sticky bonuses. In that context, if you find those formulas, this would be like a $0 deposit and a $100 sticky bonus. At least this should get you in the right mindset for how to extract maximum EV out of this promo.