This limitation is not a limitation, but a setting done by SharePoiunt and you can altere it using Central Administrator site! So, go to Central Administration and then browse to:
1) Application Management > Manage Web Application.
2) In the Web Application list, select the web application you need.
3) Then go to General Settings > Resource Throttling.
4) In the Resource Throttling window, scroll down to List View Lookup Threshold and change the value to the number that suits your needs.
This will affect the Performance so please make sure you change it as you required...