What can i do to prevent the development of ritalin (methylphenidate) tolerance?

Difficult to say : Ritalin tolerance generally *doesn't* happen according to most studies. If taken as prescribed, and particularly if someone is using long-acting Ritalin e.g. Concerta and Focalin (dexmethylphenidate) xr, tolerance to the effects of Ritalin is very uncommon. I would speak with your doctor to see if there are other reasons why it's not working for you.