A landlord who agreed to pay for some or all utilities when you moved into the park might be able to make you start paying for utilities at the end of a lease term. You should read very carefully any new rental agreement the landlord offers you. It must include a statement that, if utilities are going to be charged independent of the rent during the term of the rental agreement, the landlord must lower your rent proportionately. You can read the law about this at 59.20.060(j).
You can try to negotiate the new rental agreement with the landlord to avoid these new utility charges. But a landlord who wants to can force you to pay for utilities even if you do not want to or do not agree to pay.
If you refuse to or do not pay the new utility charges, the landlord may have grounds to evict you. Get legal advice before refusing to pay for utilities after the landlord asks you to start paying for them. See contact info below.