How many times can you repot tomato plants?

I have recently repotted some into larger containers, but still have some in 500ml yoghurt pots as I don't have enough big pots yet. All the plants are between 30 and 60cm high from the top of the soil upwards. A few have several clusters of flowers. I have now discovered Oasesbox which seem an ideal self-watering solution, and will work when I'm on holiday for 2 weeks later in the summer. However, I am not sure if I will kill off the plants by repotting them now.