Most Clearcoats can be re-coated as long as you follow manufacturers specs. Always get a P Sheet when buying any clear so you can follow the instructions for that product. Most are available at any place that sells the brand of clear you are using. Another source of info is the internet. You usually can find the P (product) sheet there as well.
I would caution the use of more coats than recommended by the manufacturer. You can run into a whole laundry list of problems doing that, one being too much product causing solvent pop and de-lamination.