As a kid that remembers having a lisp once upon a time, here are some tips to help your child cope. First, remember that your child can most likely hear the difference in how they say a word and how you say it. Bringing attention to it is likely to frustrate your child. They know they are saying it wrong, no matter how hard they try. So instead, speak to them normally. Understand that most kids don’t do it on purpose.
Having patience with your kids and their speaking will help immensely! Try to not make them feel bad for something that they most likely cannot help just yet. Some kids are more likely to limit their speech if they worry about saying things wrong and the reactions of adults or other kids. The less practice they get saying things, the harder it will be to fix it later on.
If your child has out grown the toddler years and still has issues do not be afraid to seek help from a speech therapist. They will be able to help identify the problem and help fix it quickly.