Refresh lightning component after button click

<aura:component controller="SampleController" Implements="flexipage:availableForRecordHome,force:hasRecordId,forceCommunity:availableForAllPageTypes" >
    <aura:attribute name="childitems" type="List" />
    <aura:handler name="init" value="{!this}" action="{!c.doInit}" />
    <!-- Use a data table from the Lightning Design System: https://www.lightningdesignsystem.com/components/data-tables/ -->
<table class="slds-table slds-table_bordered slds-table_cell-buffer slds-no-row-hover">
        <thead>
            <tr class="slds-text-heading_label">
                <th scope="col"><div class="slds-truncate" title="Button">Button</div></th>
            </tr>
        </thead>
        <tbody>
            <aura:iteration items="{!v.childitems}" var="childitem">
                <tr>
                    <td>
                    <div class="slds-form-element">
                        <aura:renderIf isTrue="{!childitem.show__c}">
                        <lightning:button variant="brand" label="Sell" title="{!childitem.Id}" name="{!childitem.Id}" onclick="{!c.updateCheck11}" />
                            </aura:renderIf>
                        </div>
                    </td>
                </tr>
            </aura:iteration>
        </tbody>
    </table>
</aura:component>