If the game is only available as HTML5, then I think you can license its use on game sites, but you'll need to approach some publishers for that. I haven't done this myself, so that's about as much as I know on that subject.
If you decide to export for other platforms as well, then you have the opportunity to generate further income.
So, you could just sell your game via app stores (Android, Windows, iOS etc.), and place a one off price on the app.
Or (as mentioned above) you can give away the game for free, but add IAP. I this instance most people will generally just continue to use the app for free, but a small percentage will decide to purchase some or all of the extras you've added for IAP.
And of course, you can create revenue through advertising as well.