Isn't your ORD-YOW segment arriving at 20:20 rather than departing?

Because if that is the case, you still have plenty of options to reach YOW that night, such as a direct with AC which departs at 21:00, or even earlier via YYZ.

In any case, when you are in CLE, or even IAH and as soon as you see any delay that will make you miss your connection either in CLE or ORD, you can ask the gate agent to rebook you on an alternate route which may even make you skip ORD entirely.

As jlisi984 says, be prepared: know beforehand which alternates will work best for you from IAH or CLE because if you are about to miss a connection, the UA system will automatically rebook you on UA flights with sometimes crazy routings even if there are a more suitable alternatives on AC.

(I am at 48 segments to/from ORD this year and had to pull one of those cards from my sleeve a few times already )