Mowerhappy
You can cut a new female template using your base base as a pattern, 3/4 " O.D. brass quide bushing, and a 3/8" spiral bit.
Once completed you can use the new female template with the same guide bushing and same router bit to make a new base plate, which should be the same size as your original base plate.
The size of the template guide bushing and bit is not important only that you use the same bushing and bit for both operations.
If you keep your template for future use, be sure to mark on it, the guide bushing size and router bit size used, so that you can replicate the same later.
Hope this answers your query.
Ric