可以在调用rerender方法之前清空表格数据。以下是一个示例代码：

import { Component, OnInit, ViewChild } from '@angular/core';
import { DataTableDirective } from 'angular-datatables';
import { Subject } from 'rxjs';

@Component({
  selector: 'app-table',
  templateUrl: './table.component.html',
  styleUrls: ['./table.component.css']
})
export class TableComponent implements OnInit {
  
  @ViewChild(DataTableDirective) datatableElement: DataTableDirective;
  dtOptions: DataTables.Settings = {};
  dtTrigger: Subject = new Subject();

  constructor() { }

  ngOnInit() {
    this.dtOptions = {
      // DataTables options
    };
  }

  rerender() {
    // 清空表格内数据
    this.dtTrigger.next();
    this.datatableElement.dtInstance.then((dtInstance: DataTables.Api) => {
      dtInstance.destroy();
      this.dtTrigger.next();
    });
  }
}