Fax the hotel with your request 5 days before your stay. Mention how pleased you were with the room on your last stay. They will definitely try to accomodate you if possible.
Then you have to make sure you check in and get into your room as early as possible so they don't give it away to someone else!!!
If you do not have your assigned room number yet, consider the room up for grabs even if you have officialy "checked in". You are not guaranteed any room until you have the key in your hand.
And if something is wrong with your room, please go down to the front desk and speak to the manager. I hate reading stories about people who got bad rooms and did nothing about it!! Simple things like if you paid for a Pool View room, you should have a pool view room. Don't put up with being given something less than you paid for.
-Jon