I found a cellulose thinner that is made of toluene 60-80%, acetone 10-20%, and 2-propanol 5-10%. As acetone and 2-propanol are water soluble, but toluene isn't, would it be possible to just add a lot of water and then remove it, and then end up with just toluene?
Multiple washes with smaller quantities of water will be more efficient than "just adding a lot of water" in a single wash. The toluene will be "purified" further with each successive wash. Some toluene will be lost with each wash also to the degree of it's solubility in water at the temperature of the extraction (about 0.03% soluble in water at room temperature). As stated in a comment however, distillation would be a superior method for recovering the pure toluene.