"Oh, you want to go get a change of clothes for your baby? Well, you'll have to buy another ticket for $42.99 if you want to get back in. Or... you can spend just $12 to upgrade to a Season Pass and come and go as you please all year long! So, which would you prefer, ma'am?"
Also, if this is a new policy, it's certainly possible that season passholders will be subject to it as well, so I wouldn't necessarily assume that this change is intended to convince people to get season passes. More likely, they want to force people to buy their expensive, crappy food instead of picnicking in the parking lot.
I think what Robert is saying is that gusts can purchase a season pass, and return on another day if they do want to spend the whole day locked in the park, and don't want to spend $45 to come back.
Six Flags has also increased season pass prices at its more popular parks for the 2006 season (Six Flags Magic Mountain, Six Flags Great Adventure, and Six Flags Over Texas).
FWIW, I was assuming in my first post that the same-day-reentry-ban would not apply to season passes, but just to one-day (or, rather, one entry) tickets. Otherwise, Six Flags would have to check at the turnstyle to see that a season pass had not yet been used that day when admitting a passholder.
Then again, I wouldn't be surprised if this was a test message to feel out the marketplace. I guess the only way to find out how people will take it is to leak it. I sure hope it doesn't happen for the paying publics sake.