I don't have much experience with tomatoes, but there are a few things that our lab has found that can help a bit with other species. The first is to use some type of vented culture vessel. Allowing a little bit of air flow can reduce the humidity and may potentially help the plantlets stop holding onto so much water. The other thing would be to use a gelling agent that is less "wet". For example, Agar typically results in a firmer medium than if you were to use something like Gelzan, which reduces the amount of available water and should help slow the rate of uptake.

I suggest some more myo-inositol (2-800 mg/l instead of 100) in the medium, it may be beneficial.

Thanks for the answer Max Winkeljohn , Alberto Tosca I'll try your recommendation.