When you originally set your ISA portfolio up if you use a multitude of funds then the ISA can soon become out of balance and have a volatility or risk profile that is much different to that which you signed up for.
As an example if you invest half your ISA contribution in cautious funds and half in adventurous, but over the time you hold your investment the adventurous funds grow significantly faster than the cautious funds then your portfolio will be more "risky" than the one you originally signed up for.
To counter this we employ a technique called re-balancing in which at agreed regular intervals I can restructure the portfolio to bring the risk profile back to where you want it to be. For clients who have engaged an ongoing service this is done as part of the annual review process without any additional charge. If you have not signed up for ongoing services then an additional charge would be levied when you ask for this to be done.