If your sauce is too thin, try simmering it for a bit longer on a bit higher heat (being sure to stir to prevent burning). Simmer it uncovered. This will cook off some of the extra liquids. You can also add in more tomato puree if you have some on hand. Or, if you don’t mind a little extra texture in your sauce, you can stir in some plain breadcrumbs to thicken things up.