There are actually multiple ways to surpass this 200 rep limit, each with different results:
Earning more than 200 rep with upvotes and such, you can surpass the 200 rep limit. You will only get a maximum of 200 rep attributed to your overall rep, but if you do donwvote - or get downvoted, you will still be in the green.
Any rep earned through rewards also does not count against the 200 rep limit.
Have a look at this question on the SE Meta: How does "Reputation" work?
Non-exhaustive quoting of the list from the referred SE Meta question:
You gain reputation when:
- one of your questions is voted up/useful: +5
- one of your answers is voted up/useful: +10
- one of your answers becomes accepted: +15
- you accept an answer written by someone else to one of your own questions: +2
- a downvote on one of your questions or answers is removed: +2
- you suggest an edit and it is accepted: +2
- you remove a downvote from an answer: +1
- an answer you downvoted is removed: +1
- one of your answers is awarded a bounty by the user offering the bounty: + full bounty amount
- one of your answers is awarded a bounty automatically: +½ of the bounty amount (see bounty FAQ for details)
- you associate accounts of two or more Stack Exchange network sites, and at least one of those accounts already has 200 or more reputation: +100 on each site (awarded a maximum of one time per site)
You lose reputation when:
- one of your questions or answers is voted down/not useful: −2
- a post where you had successfully suggested an edit has been deleted (reputation page shows the cause as “removed”): −2
- the account of a user who was the final approver of a suggested edit you made has been deleted (reputation page shows the cause as “User was removed”): −2
- you vote an answer down/not useful: −1
- an upvote on one of your questions is removed: −5
- an upvote on one of your answers is removed: −10
- one of your accepted answers loses accepted status: −15
- you unaccept an answer written by someone else to one of your own questions: −2
- you place a bounty on a question: − full bounty amount
- You can earn a maximum of +200 reputation from upvotes and suggested edits in any given day. Bounties and the bonuses for accepted answers are counted separately (source). Reputation “lost” from the reputation cap is not awarded on following days.
- Voted-up comments do not affect reputation.