Changing your will is something you can do relatively easily. You do not have to re-write the whole estate plan if the change is simple- it could be done through a simple codicil to your will.
For example, if you just need to update the person you have named as a personal representative, or change the percentages on a bequest, a codicil is an easy way to do it. It still requires the same formalities as the original will- two disinterested witnesses who see you sign and attest to that.
If it is anything more substantial than that, it is worth a conversation with an estate planning lawyer to make sure the changes you want to make will take effect and will not undermine anything else in your estate planning.
Even a simple change is a good prompt to discuss your estate plan with an attorney. As years go by, both laws and your life circumstances change, which could have an impact on your plans.
Learn more here about changing a will with a codicil.