Do i have to sign a new Letter Of Offer -LOO
I have been working for a company as a clerk for just over 10 years part time with a minimum of 30 hours per week (new employees are guarantied 15 hours) , on commencing employment I signed a Letter Of Offer, recently I was informed that I was only a few employees left on this LOO, now my employer wants me to sign a new Letter of offer with the starting date of employment 2018, I am worried about a few things as no information as to why I need to sign a new LOO has been given , I am told I have to sign the new contract ,do I have a choice ?