Cells reproduce by splitting in half, a process called cell division. what do cells need to do between divisions to make sure that they don't just get smaller and smaller? answer the cells grow larger so they just don't get smaller and smaller.

The cell must grow larger before going through division.

The cell needs to pass the Interphase, a process before the division that contains four stages: G1, S, and G2. Between the stages there are  checkpoints that allow the cell to progress or is denied further development.
In the S phase, the DNA is replicated so that the daughter-cells maintain the information.