Let it build up and earn interest on the interest. If you think they will rise, then keep your money in a short-term CD until rates reach a point where they are high enough to represent an attractive return for you. At that point, switch to a longer term. Plan your investing to meet those needs and goals. Keep the rest in longer term, higher interest CDs.
CDs are low risk, but offer a lower return compared to other types of investments.
Keep only the amount you need to shelter from risk in CDs.