Will I need braces again?

If the retainer is loose that means it is correctly fitted and doing it's job. It may be a little lose but not so bad. Also, your teeth are always shifiting and thats why even after braces you have to get retainers. Retainers do not have as much metal and force as braces do. The retainer tightening should fix the problem and if not, you may have to revist the metal merch!