If the Lattice device you're currently using doesn't have a PLL, or enough PLLs, you can either go to a larger Lattice device that has more PLLs, or
you add an ispCLOCK device externally:
http://www.latticesemi.com/products/ispclock/index.cfm?source=topnav
Advantages of adding the ispCLOCK can include larger divider settings and the ability to drive multiple external devices.
Another option is to look at one of Lattice's other FPGA devices. For example the LatticeECP2/M devices as all sizes of this FPGA family have 8 PLLs available. For more information regarding the LatticeECP2/M device family visit the Lattice ECP2/M web page at:
http://www.latticesemi.com/products/fpga/ecp2/index.cfm?source=topnav