Well a higher concentration of base will have more moles so more acid will be required to neutralise it. They key is the amount of moles of alkali. If you're working with consistent volumes of base then higher concentration of alkali will have more moles for than volume and so you'd need respectively increasing concentrations of acid.
If i were to keep the amount of alkali the same but changed the concentration of it, would i be able to change the volume of acid or would i have to change its concentration.
If the amount of alkali was kept the same but the concentration was altered then what was being changed is the volume (so more or less dilute). As the amount of alkali is kept constant then amount of acid needed is kept the same.
Try this: 100ml of 0.1 mol alkali will take a certain amount of acid to neutralise it.
If i were to take 100ml of 0.2 mol alkali will the amount of acid needed increase, or would its mol have to increase.