Move the string out to class level so you can change it:
Imports System.Drawing.Text
Public Class Form1
Private string2 As String = "AntiAlias"
Private custFont As New PrivateFontCollection()
Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
custFont.AddFontFile("C:\aFont.ttf")
End Sub
Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs)
Using solidBrush As New SolidBrush(Color.FromArgb(255, 0, 0, 255))
Using fnt As New Font(custFont.Families(0), 100, FontStyle.Regular, GraphicsUnit.Pixel)
e.Graphics.TextRenderingHint = TextRenderingHint.AntiAlias
e.Graphics.DrawString(string2, fnt, solidBrush, New PointF(10, 60))
End Using
End Using
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
string2 = "just a test"
Me.Refresh()
End Sub
End Class