You haven't said what baseplate you have and a picture of the table to date would be good too. I've screwed up at least 4 table tops and used them until I got up the gumption to try again. I now build my table bases to accept exchangable tops.
Here's the scoop...
If you're not using an OakPark baseplate, it is possible that changing baseplates and recutting the recess to suit the OakPark baseplate would solve the problem. The OakPark tops are 11"x11".
My problem is that I use multiple baseplates in the same holes and none are the exact same thickness. There are several "kludges" that might help. I cut my insert very carefully using the OakPark method. This means that I have some confidence in how deep the flange is. To "adjust" from one baseplate to the other, I use the thinest, cheapest masking tape so "shim" up the baseplate. The masking tape can be continued up and part way across the edge of the baseplate to "fill in" that bit of excess.
An alternative is to put gussets across the four corners and set screws into the gussets so the heads become the bearing point.
Then, there's the "fancy" solution where you insert a thin wedge of some contrasting material around your baseplate, smooth it off so it's flush with the top of the baseplate and call the solution "marquetry."
The ideal solution would be to cut a new table top, this time using the OakPark method and shiis.
Just a collection of ideas that may help.