You will need to delete any linked tables in the front end and then use the linked table manager to relink to the frontend to the backend. The new table in the backend should then be linked (along with any other tables)
If you are replacing the existing table, just click on it and hit DELETE. However, I would rename it and then link in the new table (just in case you need to reverse what you are about to do) or make a back-up copy before you proceed.