. If you have a real estate loan can you advance back on it.

What kind of 'real estate loan' are you asking about?
An equity loan - yes.
A fixed rate mortgage, not without doing a modification.

The proper use of any loan should be spelled out in the promissory note. If there's any question about the meaning of any of the language in the note, you should discuss it with the person who drafted it, the bank's attorney, or both.