Here is your problem.
1. Linking to Excel as an external table, you can see changes to the table when they are made. I.e. manual updates to the table are visible within moments after the person updating the table exits/saves or manually saves the changes. But you cannot update the Excel worksheet as a linked table from Access because that particular kind of table is linked Read-Only.
2. You can make a copy of the linked table to a local table in your database, but that is then a point-in-time copy, a snapshot. The linkage would be updated but that table took on an independent life of its own the moment the copy was complete.
3. There is no auto-update function in Access or Excel that would allow synchronization of the two entities (worksheet vs. table). If you want to know about changes to the Excel worksheet, you must examine that sheet and compare it to the Access snapshot table to find differences. This will be a piecemeal operation rather than a wholesale operation. There will be no simple single query to do this. A sequence of queries MIGHT do this, but you might be looking at some complex VBA code to assure proper results.
4. You COULD wipe out the table and re-import the worksheet, but you lose whatever data was in the Access table beforehand. This might not be so bad depending on what you were doing, but if ANYTHING in the Access table has gained dependencies (like a records in a child table) then to wipe out the table and import a new version runs the risk of creating orphan records or of violating relational integrity on such records.
To know the best course of action here we would need to know more about the data flow of this particular piece of the business to which it relates.