The only method I know of is to attempt to retrieve a value (e.g. DLookup) from a linked table that you know will always have data in one field, such as a table of users. If it fails, your connection is surely lost. Not 100% reliable but pretty close. Then you relink via code. I suppose you could always refresh the links automatically without checking, but that seems klunky to me. Checking the connection property is of no use - it won't tell you if it's valid.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.