On amazon search Buildtak and they will have replacements. Or you can get a magnetic build plate like this one just makes life easier

This is what I use. https://smile.amazon.com/dp/B07TSMW3CL/ref=cm_sw_r_cp_api_glc_fabc_WFD8Fb8QFG0Y0?_encoding=UTF8&psc=1

You will need to adjust your z stops https://www.thingiverse.com/thing:1808029